how often are you doing foliar treatments. You really only need to learn their life cycle and then treat in waves to make sure your getting all the eggs, nymphs crawlers. In short yes you can go too far.
Tough part of thrips, that some folks don't realize. They actually peirce the plants tissue with their ovipositor cut slits and lay their eggs inside of the plant and with one treatment you may catch the new hatches and crawlers, but when the buried eggs hatch its off to the races again!!!! I personally hate thrips for that reason alone. They are tough to eradicate for good.