I've been doing a lot of thinking on it, I feel it's super dependent on the MU and the flow of the match. I don't think it's realistic to camp for a second fart opportunity without reaching a point where you're either going to take too much damage yourself or doing too much damage. It's counterproductive to camp for a 60% kill move if you end up getting your opponent to, say, 120%. It's kind of abstract and I'm quite annoyed at the fact that I'm still not sure what to think of it. If camping also means you cannot react efficiently to your opponent forcing an RPS because you're trying to avoid risks, you're going to end up not playing a match efficiently in the hope of compensating all that with a fart. Isn't it weird how this is also a form of a risk? I've edged away from the thought that having a fart forces your opponent to play differently and I now think that their option pool remains largely the same because Wario's fart setups are so similar to uair/fsmash setups.
I'm rambling.
Still, I feel it's hard to justify an inefficient playstyle in favor of getting the most out of the damage you do apply. The dream scenario is uthrowing someone, uair trapping them landing five hits and then manage to avoid any confrontation for one minute and a half and magically land a strong fart. It's just that it requires so much planning that it forces you to maintain control over the flow and tempo of the match for almost two minutes straight. If you deal too little damage you're not going to get a kill in the small time window you have to land that perfect fart. If you do (much) more damage you're increasing the window in which the fart is actually usable in the first place. I think waiting for a new fart every time you whiff one is situationally strong, depends on your opponent's percentage and usually requires some sort of lead if you intend to keep doing it. Suppose you whiff a strong fart when your opponent is at 100%, is camping for a minute and a half really more efficient than just playing your normal game and allow other kill options to present themselves? Of course you can and should slow down the tempo of the match as long as it doesn't mean you're being inefficient: after a minute you'll have an additional kill option.
Suppose he's at a fresh stock and you already have a lead: sure you can and should camp, not because of the possibility of a perfect 60% fart. That's the weird thing right? The optimal moment to wait out a new fart is when your opponent is not quite at the perfect kill range which would be at very low percentages, but how often are you even going to attempt a fart when your opponent is not going to get killed by it? Ideally your opponent is at 150%, you whiff a fart and you kill him by other means, then you have to gauge how fast the match will have to go for him to get at the magical 60% so you can land a perfect fart. This means you have to control the match for what you can call 1,5 stock. At that point you're already God and you shouldn't worry about losing in the first place. Obviously this same planning and logic can be applied to every percentage but the lower your opponent is the harder it is to make a correct estimation on when he's going to die. Back to the whiff-a-strong-fart-opponent-100%: you either choose to wait for a kill move or you choose to plan ahead and go for a perfect fart. Whichever suits your playstyle most, I suppose. I dislike going for a perfect fart because in my experience I just end up waiting for Godot and then I lose the match feeling like I haven't doing anything productive in a while.
Another situation for good measure: you whiff a perfect fart. I think this is an easy one, the only reason you will camp in this situation is in a super niche situation in which you were going to camp in the first place and you have nothing to lose by doing it. I can think of being at 200% against Falco when you're both on your last stock. 'Nothing to lose' really means nothing in this context, I'll refer to what I wrote earlier about losing efficiency because you're trying to be efficient. I reiterate: it's weird how regardless of what playstyle you actively choose for with Wario, you're always taking a risk with your decision not being optimal. This isn't Wario-specific but he suffers from this particularly much. This is another reason why Wario can be played in so many ways without any of them being convincingly better. It's also why he is bad: regardless of what you choose you're either going to have to be lucky that the match really goes the way you envision it to go or, sillier, you're going to have to better than your opponent in the first place.
Of course, if your opponents don't apply pressure and you can camp as much as you like none of the above really comes into play because there is zero risk involved.
Now that I'm spouting words and discussion is going: this subject made me think a lot of how difficult a subject killing is in general. Simple questions like 'is it preferable to have a select few strong killing moves or a multitude of weaker ones?' and 'how well does X character kill' are extremely complex and hard to provide solid answers for. Is Wario good at killing? You can argue uair, fsmash and fart but truth be told the latter two sometimes just don't land, there are no guaranteed setups and they tend to require an error on the opponent's part or consecutive reads on your part. I end up finding myself killing at 170% with nairs and bairs which is fine... I think? This is a tough one. The first 60% damage you do is the most important because it forms a necessity to kill someone in the first place with a perfect fart (let's just forget about gimps for now). The next 50-60% will get you to the point where uair and fsmash will kill. After that, you'll get a broader killing pool with every percentage you deal because of position dependent bairs, nairs, odd ftilts and eventually fthrow and offstage fairs. In this sense all the damage you do is working towards something.
Still, it feels like the marginal efficiency of the damage you do decreases the higher up you get because often enough you will end up killing your opponent at 170% with an fsmash or a uair anyway in which case all your hard work from 120 to 170% feels wasted. Quod non? I don't know, this is related to the previous subject of camping out for farts and it's equally dependent on your playstyle. If your playstyle is shield-orientated you will find yourself in the described situation often enough if you don't switch up your playstyle when you have your opponent in potential killing range. Opting to do so means settling for a more risky game because even though you're making more use of the damage you have dealt you may end up taking more punishment yourself in the progress simply because you cannot force a kill with the options you have as Wario. Willingly going for the 170% to end the stock with a weaker kill option is more safe but less potentially efficient. Again a hard decision you have to make, although I suspect most people don't actively think about this going into a match. I sure as hell don't do it 100% of the time. Not every character requires this sort of thought. MK for example cannot force a kill before 150% either (against Wario) but once Wario hits that point it kinda marks the beginning of a killing era in which every additional 10% taken gives MK one or more extra kill option.
In this sense MK doesn't have to plan anything out, he doesn't have to think about a risky, potentially more percent-efficient playstyle because 90% of the time he'll end up having to bring Wario to 150+ anyway. In this sense I perceive MK to be a decent killer because he can guarantee himself a kill starting from a certain percentage. I would even argue he's a better killer than Wario in the Wario-MK matchup because Wario rely on getting a kill ever (until 170, perhaps) because even nair, dair and bair require some sort of read and in any case cannot be forced. This is a major reason why the whole weight argument is null in my opinion: living long doesn't matter if your opponent lives equally long but damage you a billion times easier. With all this in mind I can add that the only worthwhile playstyle against MK is doing inconsistent stupid broken stuff like SHFF uairing over dtilts. If you don't land early kills you're not supposed to win the match and as said: you cannot force early kills.