Man, I tried to use an unlimited 5 energy from an Academy character to chop rocks and training dummies . . . only it took 2.5 minutes for me to reload the game (because it doesn't acknowledge the unlimited energy otherwise). Then it reset 3 times while I tried to chop stuff and I watched the clock run down and my stuff undoing itself. I think I spent more energy trying to unlock the Academy character than energy saved chopping rock(s) and training dummies.

G'luck to everyone working their way through this one. It's energy intensive.