I have a pretty solid routine that I go through for practice and of course over time I expand what I am working on either more stuff or more technically challenging routines. Over time is that I work with someone every 2 weeks and adjust accordingly. What I noticed here recently is that towards the end of the practice I start getting a spitty sound to the notes and when I try to do slurs up and down above the staff I go up then down and can't go back over again. This is usually when I say ok I have practiced long enough and can't practice anymore with where my chops are? SO is this a normal thing that is a sign that you need to stop practicing and come back to it or are there things that I should be doing so that I can practice longer, keep the notes more open, and maintain the upper register?