Labeling folders so I know when they get "too big"

When I run low on disc space it's always a chore to figure out which folders are bloated and which files can be deleted. What I'd like is to have Hazel keep track of which folders in my home folder surpass a predetermined size.
If I create a rule...
Kind: is folder
Size: is >1Gb
Action: Label Red
...is Hazel going to periodically calculate folder sizes from scratch? I fear that's too cpu intensive for my G4. Is there a better strategy than this?
(Has there been any discussion/requests about being able to schedule _when_ rules are run by Hazel?)
If I create a rule...
Kind: is folder
Size: is >1Gb
Action: Label Red
...is Hazel going to periodically calculate folder sizes from scratch? I fear that's too cpu intensive for my G4. Is there a better strategy than this?
(Has there been any discussion/requests about being able to schedule _when_ rules are run by Hazel?)