Russ Allbery wrote:
The one exception I can think of is if someone really wants to customize the [spamassassin daily] job. That can be a little more tedious to do with timer units. Right now, I think there's a bunch of logic in the /etc/cron.daily script that someone could in theory change. But I'm not sure how often that happens or how useful that would be.
I've modified that script in the past, to add third-party rule sources. As far as I can see, in the current packaging if you wanted to do that the simplest way would still be to modify that script. Though I don't know if there are any useful third-party rule sources these days. -M-