Several years ago there was a Q about how OCD-ish people were about keeping their Q For You lists updated and trimmed of excess.
At that time there was evidently no algorithm in place to auto delete with the total cap being 1000. John Powell posted an impressive looking screenshot of his totals (which were sky high and several thousand) along with stating that he never deleted any of them or even paid any attention to it at all.
I was inspired to do the same just to see how high a total I could get since I use the same approach as @jonsblond. But then at some point subsequent to that, I started noticing that the cutoff point was 1000. Too bad. That took all the fun out of it for those of us who ignore the Q For You list :)