NOTE: I have the Litter Robot integrations with Home Assistant and bringing it over to HE using the HADB app.
I spent a bit of work perfecting this rule so I wanted to share it. Much to my surprise it really gets the desired result, which is other people will take care of the cat box besides just me every single time.
This one alerts when litter level is 90% or lower, once it hits 80% is starts repeating every 30 minutes.
This one alerts when waste drawer is over 75% and once it hits Drawer Full (dfs) then it starts the repeating alert.