Although I can see the frustration I like it.
First of, I find it kinda funny that low wits could make you a slow learner, when you try to master a new talent (remember its only the first rank - so a trainer isn’t that inappropiate anyway). Second, I don’t find time wasting a problem - I actually think it serves a purpose in a game where resources are scarce. I personally like it when the players have to stop and think for a moment - and decide whether or not they should try to master that new talent right now, in the middle of a dark forest or such, or if they should wait until they’re safely back in the village.
That said, as a gamemaster I want everyone to have fun. So if frustration sets in, I’ll throw in a random event to liven things up.