It's a good idea to test and train both sides. If you find one side needs more attention, spend some extra time on that side.
For example, if one leg is stiffer when you do a hamstring stretch, you'll want to do extra stretching on that side. If one glute is weaker than the other, then you'll want to do extra glute reactivation work on that side.
It's simple to put this in practice.
If you are doing a hamstring stretch for two sets, do an extra set for the stiffer side for a total of three for the stiffer side.
If you are doing a glute exercise for two sets, do an extra set for a total of three for the weaker side.