It's not trivial for me. All my life I've struggled to attend to scheduled events that are not regularly recurring. I've missed midterm exams in college. I've missed band gigs I was scheduled to play in. I've accidentally stood people up in social outings. I've missed credit card payments. (solved that one with auto-pay) I have calendars and email accounts, and they usually work, but sometimes I miss the notification or forget to check the calendar.

For me, if I was going to plan to cancel something in the future, then instead of scheduling it, I'd just do it now before the thought goes out of my head.