This exercise is a trusty old favourite. I have seen similar in various books etc. I have also heard many professionals playing variants of this exercise as they take their trumpet out of the case and ‘pootle’ around before practice, rehearsals or performance. It is ‘tried and trusted’. Good exercises don’t have to be new to be good. I have quoted the great trumpeter William ‘Bill’ Houghton before in these posts, “…Don’t employ wicky-wacky methods!”
Try the study tongued, as well as slurred and don’t be in a hurry. Personally, I find the slower I go the more I am studying true control. I profit more from this type of study than playing ‘lip slurs’.There is nothing wrong, in my view, of taking a decent breath at the beginning and if necessary, taking another when needed! Sometimes I mess around with the rhythms too…
Of course, there is no magic in this material, particularly: like any other study, it is how the material is honed that makes the difference.