Some people take practice tests until they hit a certain score and then pause with the prepping. That is never the right call. You also have to build consistency. Having a good score one day isn’t enough because you still have to account for the bad test days.
Oftentimes, people feel confident on their practice tests and start doubting themselves on test day. Sometimes test day just feels very different from their practice days because of noise, a bad breakfast, temperture, or some other factor. It takes a lot of consistent practice to be able to feel confident regardless of the testing environment.
I have my students take enough practice tests in a variety of locations so that their test day feels just like another practice day. I try to get them to the point where their test day will feel just like one of their practice days.