The variation in energy recovery is minute though. Recruits start with 50 to 60 TUs, meaning that they have between 16 and 20 energy recovery.
Since a soldier uses 2 energy per step, he maximum difference is 2 steps per turn once exhausted, between your best and worst soldiers. And like endershade mentioned, energy improves with experience, making it less and less likely to matter.
If you run, a step is 3 energy, so even less of a big deal.