Generally speaking, being too big for anything (condoms, greek, d/t) is not a concern for moi. However, I do special order my own condoms from Japan and quickly learned not to get the "regulars". Like trying to use a finger cot. Good for the ego, though.
The problem isn't getting it on, the problem is circulation....
Ever put on a latex glove 2 sizes too small? I'm sure if you were careful, you could get it on and be like hey! See! it fits! ....as your hand starts to go numb from lack of blood...
The problem with a condom being too small is that lack of circulation = limp dick = no fun
There's a reason for condom sizes. I've had a condom put on before that literally covered half of my dick. Just kinda looked at like the little condom that could.... except it totally wasn't going to work lol.
Yes, it is possible to be too big for a condom if the right size isn't available (those gold wrappers work wonders). And if you're running around with a dick that big, you damn well know that not every girl carries gold wrappers, and that you should have at least one in your pocket just in case.
I have met guys that are thick and regular condoms or even regular magnums are too tight and need the XL. I agree that it is blood flow, not just whether it fits or not. If it is too tight and restricts the blood flow, not all guys can perform or stay hard. I knew one guy that preferred regular even though Magnums fit better because it was like a cock ring to him. Cock rings are meant to restrict blood flow and keep a guy hard, however too tight and it causes pain from what I've been told.