Yes .. to the question raised in your last paragraph. If you do anything "not masked", then it does not run the default handler. If conditions, match conditions and while conditions are naturally masked. Anything inside a : mask {} command are masked too. I think I documented this somewhere.
Ah, here it is:
https://adventuron.io/docs/tut/index3.html#MaskingCommands
Everything is an override by default. You only need to use : done; if you absolutely want to stop processing, but done is quite often not required to stop the system handler for a system command running. Doing a print of set_integer, or set_boolean, or any non passive command is enough to stop the system command handler dead in its tracks.