It would be cool if you could do a recurrence. Ex: I was sick all week, so I want to enter a Health Note that starts on Sunday and ends on Friday. This would work good for setting up training plans(ex: Tempo Run every Friday for 4 weeks, weights every Tue/Thurs for 6 weeks)
Swim , Bike, and Run A LOT
I can see the value of spanning an event or health note across multiple days. I've been wanting to do that but haven't done it because it is somewhat complicated.
As for recurrence, unless your training period is very long, it might not worth the effort to add such a feature because it's pretty quick to just copy an existing workout by dragging it to the new date.