They generally advise against shooting a defensive carry pistol further than 10 yards or so. They say shooting an assailant further will get you into trouble.
I don't see it that way at all, but there is a filament of logic to that.
Realistically, one will likely not be faced with a situation in which a threat of deadly force is imminent unless the apparent threat is close.
Let's define "close" here as seven yards. The idea is that if a threat with an impact weapon starts moving from seven yards out, ir would take the time that a fit person can close that distance for a defender to draw and fire one shot.
Obviously , the distance will be mush less than seven yards. Think arms' length, and think movement.
The idea that shooting further will get you into trouble probably comes form an assumption that at such distance, an attacker with a contact weapon would not have the ability or the opportunity to harm the defender.
But at our seven yards, he would be able to gain that opportunity and ability, should he so intend, before the defender could draw and fire.
The defender would have to draw very fast and fire quickly, probably firing several shots rapidly.
If you cannot draw and fire at your range, practice drawing at home with an empty gun. Don't draw on something directly in front of you. Turn to identify it, and draw while moving off line. Try for less than two seconds from concealment.
At the range, forget group size. What will likely be faced with is the need to but three to five shots into the area of a small pie plate five to ten feet away at mot, in, say, one to two seconds, not including the draw time.
I hope this helps.