Are grabs viable for punishes?

[abx]

Maybe it's just me having trouble transitioning from Smash 4 (it takes me quite time), but I honestly don't know how to grab anymore. When the opponent whiffes some move and I have to run a short distance to grab them, they either get away or throw out some move. And out of shield grabs (no parry) come out too slow as well. I only manage to grab when I predict when the opponent is throwing up a shield (plus conditioning) and on some very laggy dash attacks against shields.

But maybe I'm just missing something. What exactly is there to know about grabbing? Might I be doing something wrong?

 

[Arrei]

Dropping shield in order to grab isn't going to be a valid punish in most cases. It could still work due to your opponent expecting an attack instead, but between shield drop and grab startup that's at least 17 frames for even the fastest grabs, plus however long it took to run at your opponent. That's more time than most aerials' landing lag, and a large majority of ground moves will recover before you can get to them if they were spaced well. People are advocating jumping out of shield as the option of choice these days, if OoS moves aren't an option.

Getting grabs in most cases usually requires your opponent choosing a wrong option against your predictions or your pressure, like you said.