I did read what you posted. No need to act condesending.
It's not even that I'm trying to be condescending, but moreso of a genuine belief that your understanding of how the games mechanics play out at a top level are extremely limited by the examples and descriptions that you post.
Yeah it works on more than half of the characters, but not all.
What does that even mean LMAO
it's not dacus magically is not effective againt certain characters. It's viability certainly, but the mechanic dies not change.
It is difficult with Marth and MK Fairs, but I've caught a couple Marths where they spaced Fairs, then they trip or incorrectly space, I DACUS, then they get killed off top. It's all about reading your opponent as to what they're going to do.
The situation you used sounds ********, why would marth dash after spacing fair away from jiggs. Sometimes perhaps there is a reason, but assuming he spaced right it doesn't seem like that would make the best sense.
Secondly, after that you assume they trip (the chances, and ROTFL at talking about reading after that). Then mispace. If you see a mispace you definitely should punish, however even then at even a mid/high level the margin of error for marth isn't to big in comparison to his other MU's vs jiggs.
In regards of ease of use, it should be in the discussion because there are some characters where DACUS is harder to pull off. For example, Link's and Snake's DACUS, in my opinion, are very simple to puff off...but Falco's I have difficulty with. It's in discussion because it's one of Jiggs kill moves, which Puff players should learn how to do.
I think literally all dacus's, including bdacus are easy. (unless the margin of error is under 10 frames, i.e. a really low single laser with falco, or during the landing/dead frames of an empty sh w/ no actions, or drop shield).
So that should mean that in regards to MU discussions we should assume all dacus's including falcos are easy enough to be able to pull of in all situations consistently, except oos or before silent lasers.
see what I did there?
Ledge snap adds ledge pressure off the stage. I'm not saying it's something you have to do it everytime, but if you're far away and someone slowly gets up on a ledge, just DACUS to push them back off....then space a roll then bair, fair, or whatever you want to keep them off.
This would be extremely character specific, and most of the time the best you could hope for is to reset to neutral, aka them being on the ledge.
Let's take a character with at best mediocre ledge options, such as Mario.
If he standing getups, either before or after 100% you have 4 frames to hit him before he shields, with a move that you have to react or predict the getup pretty early with.
Assuming you try to react with said move, it's going to be even harder to time. Knowing this, and knowing the fact that most good players will either shield, or buffer something after standard getup they will probably get out of the way.
Lets say they spot dodge or roll, both punishable options if you had a double read, but if you miss the 4 frames + extra few frames of startup from the defensive options, you're position is now reversed and you are now in a position to be punished.
Let's say you just picked an option like sh fair instead. Because you can always opt to just DI back and remain safe, and keep your opponent on the ledge with an uncommitted option, even if you misread you can always remain safe. If you hesitate and your opponent got up but you backed off, if they buffered a roll or a spot dodge without thinking you are in range to punish, and if they do nothing you still have stage control.
The move comes out fast, but it's super slow afterwards, which you can be punished for. It's like that with some DACUS' though, like Wario's or even Wolf's. It's why I'm saying when you use it, do it more then the opponent is towards the ledge so when you or the opponent slides off they cannot punish, or use it when you know for sure it's going to hit and kill.
The moves startup is not fast. Wario's dacus I won't even go into, but at least wolfs has broken disjoint, combo ability, and solid reward. Even then it's not really spammable.
Pushing to the ledge with jigg's dacus isn't even that great because of the range and commitment to the move that she has to have before she even does it.
Everytime you throw it out, it's a risk/reward siuation where you can either take stock/get better positioning, or lose a stock/get hit.
There are very few situations where I could genuinely see you actually getting better positions with dacus, if any at all. TBQH i think if I know you are going to dacus me, I could probably punish you with a lot of characters even if I was shielding at the ledge.
Getting hit vs not getting hit is not a good thing for jiggs to go through, so the only time it's really worth it to do is when it will definitely kill even with solid sdi.