I know this is mac specific, but since op is looking for personal infra level tooling/scheduling, there might be an equivalent what ical offers: create ical ev

I know this is mac specific, but since op is looking for personal infra level tooling/scheduling, there might be an equivalent what ical offers: create ical event+repeat+alert=Custom(Open file) this will open a file every repeat event. The file can be shell/workflow or whatever you want to run.