It would be super helpful to me to have a calendar reminder that succinctly said "you said you wanted to do this every 6 months, and now it's 23 days overdue" (and then when I finally do the thing, schedule the next one for 6 months after that day, not 6 months after I was supposed to do it in the first place).
Various "habit tracker" apps do this pretty well, but they don't fit in with my calendar.