I'm not a good trash emptier. I don't like the idea of doing it automatically as I'm sure that something valuable will be lost when automated. Therefore, I just keep throwing stuff in the trash until I'm getting low on disk space or there is an insane amount of trash. I created a simple macro to show me how much space the trash occupies.
Trash Size.kmmacros (2.7 KB)
I run this from menu and it shows me this: