Board Thread:Questions and Answers/@comment-35732832-20180530120326/@comment-27664094-20180604040843

I don't know anything about kill grinding and which room is best (is there even such a thing...?), but I do know this:

Please specify which region you're in so that those of us who have not memorized all of the kill counters can help you.

Remeber that as you kill monsters, encounters become less and less frequent. You're probably seeing that effect. Toby Fox designed it that way because it makes sense and to make sure someone doesn't unintentionally initiate the Genocide Run so that the game has the right to berate you for doing it because you can.