When I look under the /DesktopModules/ToSIC_SexyContent/Upgrade/Log folder, it seem that everyday some files get written there. Is there a way to stop this?
There is no safe way to do this. It is necessary for various situations where initialization code could be running simultaneously (like when the server is just starting, and multiple requests cause initialization before the first initialization completed). Since this could happen in a farm setup, a variable wouldn't work, so it has to create the "lock" files.