There are basically two things to be aware of here:
The grip itself
The repeatability of holding it.

If you vary where the pressure is being applied, then you vary the natural point of impact. Think about this. Lots of little finger pressure has a lot of leverage on the bore line up and down. Thumb pressure can pust up and down or side to side. Etc etc.

When you shoot when you are hot and sweaty, or cold, or in the club on your own, or at the biggest match of your life with coaches and photographers everywhere, I'm willing to bet you dont grip with same consistency.

So....
You want to adjust the woodwork so that when you squeeze you impart minimal change to the point of aim. So point down range, and try it. Think about what forces are applying where, where does the sight picture go if you ease off the tension slightly. Think what you need to learn, and what can be adjusted to minimise the effect.

Ok a little offf topic, but just saying there is no magic right and wrong answers. The sport is an art not a science.

In general, hold the gun only as tightly as you need to stop it moving when you vary trigger pressure. Remeber, you will be applying at least 500 grams of pull, on a tool which only weighs just over double that, so your grip strength needs to be sufficient to not allow that trigger pull to cause any movement.

Oft used measure is "as if you are shaking the hand of a child"