Honestly, it is tiresome trying to wade through all the "this is why you are missing" type videos. You will hear: It's your grip. It's your trigger control (I think this is mostly it!), stance, where you put your finger on the trigger, how you sight, sight picture, breath control, etc.
I think a great grip is good. But what if there is a time when you can't get that "perfect grip" ... you know, like when you are under great stress.
My experience is simply that, grip it and hang on tight and focus on the trigger control. You can have the perfect grip and if you are yanking and snatching the trigger...it's going to be no bueno every time. The reverse is also true.
I've seen genuine experts shooting dead-nuts on holding the handgun upside down, backwards, from all kinds of funky grips, weak side one handed, etc.