I agree. It might make sense to have lessons from a few different instructors early on to get to know the different instructors and find out which one suits you best (and at this time you're not really forming bad habits anyway), but after maybe five lessons you should continue with, preferably, one instructor for the core of your training.
It does make sense to fly with a different instructor every now and then though, to serve as a sort of "stage check". Instructors are human too, and they might miss something that'll be picked up by another instructor. But in those cases you really should be undertaking that lesson as a stage check/consolidation lesson, instead of a lesson where you're supposed to learn something totally new.
I guess the typical moments for such a stage check are pre-solo, pre-cross-country-solo and an end-of-course checkride, just before the exam.