Well, systemd developers made one of the classic blunders a software developer can do: make a program that has to deal with time and dates. Every time I have to deal with timestamps I’m like “oh shit, here we go again”.
Anyway, as I understood it the reason this is in systemd is because they wanted to replace cron, and it’s fine by me because cron has it’s own brain-hurt. (The cron syntax is something that always makes me squint real hard for a while.)
Well cron is “really easy” as long as your requirements are really easy too.
Run a task at specific hour or minute or weekday or whatever? Easy peasy.
Run a task at complex intervals? What the fuck is this syntax. How do I get it right even. Guess I’ll come back next week and see if it ran correctly.
Actually have to look at the calendar to schedule this stuff? Oh lawd here come the hacks, they’re so wide, they’re coming
Run a task at, say, granularity of seconds? Of course it’s not supported, who would ever need that, if you really need that just do an evil janky shellscript hack