Why do you think so? When I'm on a platform I feel like waiting for my opponent to either attack or land on the platform to a shield drop is the safest option to get off the platform.
It may very well be the safest option, especially vs. players that are either not that good in general, or bad at dealing with shield drops because they've really just never had to before. The problem I have with it is that it puts you in the mentality of "Oh crap, I landed on this platform, so now I have to shield and hope they do something dumb." Once good opponents catch on to the fact that you are shield dropping, they start doing things to get around it. They will feint an attack and try to punish your drop. They will actually hit your shield, but space it so your counterattack whiffs and they can punish it.They may just wait while your shield shrinks, and suddenly what turned into your go-to gimmick has you in a horrible position. You end up above a character (almost always super awful positioning), low shield health (they can attack at any time and you will be vulnerable to pokes), or you just realize that they are waiting and jump. That last option may sound just dandy, but the longer you wait in shield on a platform, the more likely they will be to swing because they know you are more likely to abort your shield drop plan.
All of these mixups only become possible once you make the decision to shield on a platform. If the alternative is really that much worse than the situation I depicted above, then by all means shield and do your best to get out of the situation however you can. Most of the time, however, I notice myself shielding on platforms when I don't need to because I am in the mentality to get shield drop counterattacks. When I am able to resist the temptation of a seemingly risk-free shield drop punish, I find myself getting away safely much more often. So if you have two players, one who relies on shield dropping and one who doesn't, the one who does will definitely get some good counterattacks, and he will even be able to escape largely inescapable situations. The other player may just get hit every time in those situations where shield drop is necessary, but in all of the other situations he is maintaining dynamic movement where even if his opponent plays properly, he still has a chance to outplay him. Barring a few outlier situations, you can't outplay someone from shield. You are simply limiting your options, and most importantly, your movement for no reason. If shield dropping or shielding in general is working against someone, chances are they are outplaying themselves.
This is why I think it's much more important to get the skills for all of the different escape scenarios first. Learn when you should jump, learn when you roll, learn when you should hold shield, and then once you've really explored all these options, you can start shield dropping in scenarios where you know in your heart you have no other options. If your brain does its systematic option-check when you land on a platform and you can't jump, roll, CC, hold shield, or do anything without posing a risk greater than a shield drop, then you can go ahead and shield drop. If it doesn't work, then at least you got punished knowing you made the right decision to survive, and not just the easiest/simplest decision of "I'll shield on the plat and hope he outplays himself!"
In a more broad sense, I think this really fits in with the mentality of making purposeful decisions. I'm really starting to appreciate the benefits of active decision making vs. passive decision making. One of the core principals of things we label gimmicks is that they are largely passive. You aren't deciding to shield when you land on the platform. You have defaulted to shielding and occasionally make the decision to NOT shield drop. This mentality seems to make people extremely predictable in general. I know I used to, and to some extent still do, struggle with teching. It's not because I make poor tech decisions. Rather, I don't make tech decisions often enough. Too often I default to tech in place because tech in place shine worked all day on my training partner's Marth when we were both really bad. Then fast forward a year, and now he grabs techs in place on reaction almost every time, but I am still in the habit of teching in place. It crops up most often vs. Falcon because Falcon's anticipate techs in place religiously. The amount of knees and stomps Falcon players place in the tech in place area are ridiculous, yet when I'm focused on my DI or other things, that habit of teching in place bleeds through my gameplay and becomes a huge weakness.
DI is another thing that new players frequently disregard as a passive habit as opposed to an active decision. I'm sure everyone's seen someone take 20 Marth fairs into a Ken combo and wonder, "Wow, why did they DI in that whole time?" It's because they learned to survival DI first, and thus it became their default mechanism any time and every time they get touched. I understand why it's simpler and probably more effective for new players to learn survival DI before combo DI, but the process of breaking the default habit later on is overlooked way too often. Melee being the unforgiving game that it is, this means many players will lose almost all of their tournament matches early in their career because of these default habits. Once their opponent figures out their defaults (which are almost universal because of human nature and also because things are often tought in the same general order), they destroy them. A huge reason I believe new players can be discouraged is because they don't feel like they're getting outplayed. This is because their DECISIONS aren't being outplayed, but rather their LACK OF DECISIONS. If a player doesn't even realize that his brain has set his default DI decision to SURVIVE, then of course he's going to be bewildered and frustrated when he loses a set almost entirely from punishes designed for survival DI.
And, LOL WALL OF TEXT, that's why I don't recommend learning shield dropping very early on. If you want to learn and apply it, that's fine, but the way I have always learned is to spam something until it becomes habit for the necessary situations. Shield dropping is so difficult in execution as well as deciding when to do it, you pretty much have to just dedicate to shield dropping all the time if you want to learn it in any discernible window of time. If you can discipline yourself to practice shield dropping only in situations where it's the only way out, then by all means give it a go. I just know from my own experience that I couldn't possibly have learned it like that, and even now I'm still backtracking a decent amount trying to weed out all of my unnecessary platform shielding preventing me from properly engaging my opponent through active decision making.
). They can probably SDI out of a grounded shine-bair though, depending on the character and %.
