Just noticed that Interval scheduling doesn't support a Monthly schedule. If I pass P1M it schedules the flow to run once every 30 days which is not correct. I know we can use cron scheduling but it would be really nice to be able to use ISO-8601 interval definitions since we use that for everything else and it's clearer IMO.

Hi Jacob! If I'm understanding the behavior correctly, I think you're running into this issue because Interval scheduling relies on a precise and consistent interval (e.g., 30 days, 1 hour). Since months don't have a consistent duration, the scheduler cannot directly translate

P1M

into a recurring "first of every month" or similar pattern.

Thanks Bianca. That seems a bit counter intuitive to me but "time" in software is a messy nightmare so I won't comment further on that. With that said I do think that it's unexpected behaviour for the scheduling interval class to accept

P[N]M

at all if it's clearly not supposed to be used this way.