I noticed that the food that occurs most frequently is the food that gives the lowest JP, regardless of where the food is located on the list. I know this to be true because I leveled up my Oran Berry to have more JP than my Sitrus Berry and then suddenly the Sitrus Berries occurred more frequently than the Oran Berries.
My question is: does training do the same thing?
By the time I realized this about the food I had been focusing on leveling the training session that was the farthest down on the list (like Pokeball Smash). I know that a training session like Pokeball Smash already felt rare to me, but would I be harming myself in leveling just one training session? Would that training session scale so that every other session is more frequent? Would I be better off leveling training evenly?