I've not done slurs to build range because I don't know what to do. From which note, to which do I slur? How long should I do this (how much of practice time)? Please, if slurring has worked for you, I ask what you did, in detail. If I don't have something already proven to work (even if only for a few people), I will have to make up something on my own, which will not be consistent from day to day, and before long I will not practice slurring.
I also have Complete Lip Flexibilites (Vol I-III) by Charles Colin. What should I do with that? I played the first exercise and etude (which was to play so many slurred notes in one breath; I couldn't do it) for a about a week. With no noticeable improvement, I gave up and haven't opened the book since.
When you do exercises that say: "do x in one breath," or whatnot, do you just over when you mess up , and keep trying for a few minutes and move on to something else?