By edge, I mean that optimal alertness ....I find my mind wandering.One technique I'm employing to combat this is to go for 5 repetitions of a section perfectly, and if I flub a repetition, I start again at the first repetition till I complete 5 perfect repetitions.Realistically, I know that I can't be optimally alert every moment, but I'd like to employ whatever techniques I can.
It might sound crazy but photocopy your music and cut out the chunks you are working on and paste it onto a single page of some exercise book.