This is what Tech himself said "Hello SoupDragon, if you are set to 100 it starts with 200 and then whittles down from there. I didn't really think people would use it to ignore more than half of the threads. We can change so that it starts with more than that or summink. I'll fix overnight to start with 4x rather than 2x. You'll always be able to get it to go under your 100 if you try though, as it only ever starts with the last day, so if you were to ignore all 1500 (average) threads that are active in a day, you'll end up with none even if you were set to 100 (iyswim)."
It took a while to find my thread!