Training lessons

Hey guys, I am really sorry if this is posted somewhere and I didn't see it (though I searched a lot just now). I think I got the hang of the game by now, but there is still one thing I could not figure out until now. This is concerninh the training lessons with the teachers: What benefit do I get from those except for unlocking the gadget slots? I mean, it says HP +4% for example, but I couldn't see any change in the stats of that character's card(s)? Am I just stupid didn't see it? Maybe someone can help me, thanks :) via /r/BnHASmashTap http://ift.tt/2sTkrGa