If I have the Essence for it (and the Willpower), can I activate two instances of Harmious Academic Methodology at once? What about the Tiger Warrior Training Technique? Or the Bestial Traits Technique?
No. Training is a single Dramatic Action. You can't do more than one Dramatic Action at once, therefore, you can't do more than one activation of that kind of Charm at once.
That is, unless you are a Lunar with Ant and Starfish Trick who has been lent the charms by a Solar with Charm Lending Method and you are training two separate groups of people. 8)
Rats. At the same time, training someone for one hour a day for a week seems to leave a lot of time for... Other things, including stacking them into one Glorious Solar Realized Curriculum that essentially provides a crash course in BEING A SHMOT GUY in a very very short amount of time. Essentially, HAM and TWTT are the 'training montage' powers, and I like that idea a lot.