I've been a year this May, and I definitely feel sharper than I was then. Full time instructing teaches you how to deal with long days and dealing with people. This time last year, I was still trying to finish school, instruct, and have some sort of life with the time that was left. After 6 months full-time, I'd say you find that balance that works for you.

As for training, look at it this way: Most students don't really know how to learn, they cram. That works well for classes you don't care about, but the skills that have been drilled into your brain will serve you well at your next job.