What is your specific question? as stuart mentioned we all have a dominant side, and we see it in students from lesson one. All of the drills should be practiced on right side and on left side. The dominance is an issue more for coordination rather than strength.
The most common issues I see regarding dominance are
-dominant side is less flexible
-non-dominant side is less coordinated
I've never, in teaching kids as young as 7 and adults as old as 80, seen someone lackign strength to do the recovery motion.
Also, single arm freestyle can be done breathign to each side. Right arm only breath to right or breath to left. Left arm only breath to left breath to right.
There's no issue finding & identifying problem areas...to address get feedback through
-on deck observation (lifeguards can do this sometimes if you ask them what to look for)
-Video feedback, even from still photos
-self perception seeking symmetry