Hello. You asked for date/time examples. Here's one I've found especially perplexing. I'm a financial planner. When I advise on how college savings should be allocated, it depends on how many years until first and last withdrawal (these in turn depend on current grade level and how many years of college are planned). Once I determine the child's grade level once, I don't want to ask again.  I want to be able to calculate subsequent grade levels automatically and, from that, how many years to first and last withdrawal.
I assume a grade ends on June 30th and college will be paid for on June 30th for Fall enrollment.
The challenge I've had is that I can't go by calendar year to determine current grade level, the answer differs if the current month is March or September.
My best attempt has been to calculate the latest  June (even if that was in the prior calendar year) and subtract that date from the anticipated college graduation date in order to determine how many years to last withdrawal. Would love to hear if you have a better solution. Thank you.