Agreed. It is like someone who can barely bench press 150 lbs and they shake the entire time. Versus someone strong enough to bench press 200 lbs, but calmly pressing 150 lbs. A strong grip makes the whole process much smoother. All the shooters I know have very strong grips then exercise a smooth, consistent squeeze. Do you ever do one handed shooting? My Dad does it as a form of practice.
Boo
I shoot equally using the typical two hand grip, single hand strong, and single hand "support" (using left hand only). I also shoot from about 8+ different stances. I shoot prone both on stomach and back; both knees down; 1 knee down; weaver; modified weaver; isosceles; one hand target (turn full sideways); while moving laterally and forward/backward; and then when able I do all of those stances using the "support" hand alone, too. But for standard shooting technique I usually split between the three grips (dual, 1 hand strong, 1 hand support).
FWIW, research has shown that no matter how many times you practice using the weaver or modified weaver stance that by some genetic default our bodies will typically use the isosceles stance if given the chance. Some researchers think it is because for thousands of years humans have "engaged" a threat using 1 arm as a shield or for balance and the other to strike and the isosceles stance best mimics that. Anyone's guess though. I always teach to stand like you're going to punch someone, it seems to provide the best balance.