According to Bisqwit of TASVideos, you need to clear 18 Mansions before you enter the game's loop.

Alternately, it could be until the end of the loop after (Mansion 16) due to the mice's increasing speed.

He is correct.

In case of confusion with the "Beat All Rounds" category, Round 16 is exactly same thing as round 1 with already faster enemies and different door spots, I decided to add the category "Beat All rounds" goal up to 15 (15 being a bonus) because 14 is the last legit different level of the game.

1 loop category can be considered as a new category, if so, I would like to hear opinions about it.

The strategies for the following levels are exactly the same as they are earlier in the run. I think the current end to the run is fine.