Why?
In competition, you never know what throw your opponent will attack you with, so you can never know what grip you can end up with to counter.
Instead, I teach my students the mechanism of the throw so they can apply it from whatever grip they have.
Here is the most important mechanism you should be paying attention to; create a belt around your opponent’s waist. That is the most important thing.
At least, one arm should be wrapped around the waist of the opponent, this is how you are going to lift them.
The other hand can support the lift by gripping the lapel, shoulder or anywhere your fingers can grab the gi.
Just use whatever grip available, you have a very short window of time to counter-attack, your reaction has to be quick, don’t waste it by thinking about the ideal grip.