Couple of years ago I was having a hard time with my 1911. Great big "groups", like the size of a huge dinner plate.
Paid about $80 for an hour of one on one instruction.
Instructor had me shoot a magazine. Then he corrected my grip, explained what and why he was doing it. Instant improvement, huge as a matter of fact. So we had a lot of time leftover, I shot a bit with him watching then offered to let him shoot the 1911. I said "Aw, cmon, I would like to see a really good shooter. . ." He said, nope, he was actually worse than I was. I did see him shoot later, and yup, he was worse.
The point being that if someone knows what is supposed to be done and can see the other person doing it wrong and then get them to do it right, who cares how the heck they shoot? Certainly not me.
BTW, the $80 was totally worth it.