Beware “DONE” shifts on repeating events

In orgmode you have several ways to make a repeating event. One of the ways is to simply incude an active date under a headline, and include a repeating directive in it like so:

<2023-09-18 Mon 12:30-13:30 +1w>

This is fine, for example, when noting someone’s class schedule (not my own where I would need notes for each individual class).

 * TODO Bill's Schedule this semester 
<2023-09-18 Mon 12:30-13:30 +1w>
<2023-09-19 Tue 11:00-16:00 +1w>
<2023-09-20 Wed 12:30-13:30 +1w> 
<2023-09-21 Thu 11:00-15:00 +1w> 
<2023-09-22 Fri 11:00-16:00 +1w> 

However, if you ever make these under a TODO item, and then mark it “DONE,” be aware that it shifts the times of every one of these entries by the +1w, not just the one for today that you probably meant. Obviously the answer with most things is just not to treat them as todo items. It was just an error I made because of another item I have deliberately on +1d with TODO (my daily email and planning item, which should show in every day’s agenda and holds and counts many sub-items that get their own TODO).