The only thing you can count on is that each experience will be different. That is what you need to be prepared for.
Ive generally used my own non-tsa padlocks, but with all the ambiguity and outright contradictions I keep an entire spare set of 4 TSA locks inside the case with a nice huge note that reads: TSA: “if you need to reach me my cell# is xxxx, here are spare locks in case there is any issue with mine”.
Ive never had to use them, but read enough horror stories to want to be ready for whichever way todays tsa whim blows, ie demanding I use one set of locks instead of the other, lost keys, cut open, etc.