I suggest they just load one shell at a time for awhile. Suddenly they are breaking 2-3-4-5 birds in a row. By loading one shell, they find it easier to remember to do their pre-shot routine before each shot, and they are actually practicing not only their shooting technique, but also reinforcing their routine. I find that perfecting the pre-shot routine is probably to most important part of practice for the intermediate to advanced competitor.
Practice with a purpose, and have fun doing it!
Will and Elizbeth
Fennell Shooting School