Generally, I rest my players so that their conditions are 97-99% when next match will start. My selections on training types & intensities for a player are based on the average conditions to be consumed. I don't seriously consider effect of training on injury rates as I think these are random.

For example, I will set target to train a players to 82-85% condition if next match will start after 3 resting time (i.e. 15% will be recovered.) If a players' current condition is 99%, I will probably train him once for high intensity cardio (use about 11-12%), and then once for light or high intensity stretching (use about 3% or 5% respectively) depending on result of 1st training.