Imagine, that one is able to start work at a time, when he wants to (in Germany it’s called “Gleitzeit”). An alarm after x hours after fell asleep would be a great help to improve sleep quality. This is also a good feature for weekends or days without the need to go to work.
Idea:
Set a minimum sleep time, e.g. 7 hours 30 mins. SaA should now, after start, wait for the user to fell asleep (sleep/rem detection). Then it should start the countdown. After the countdown is up, it should have a smart period, like it is already implemented, of x minutes, to detect light sleep phase. At the light sleep phase the alarm should ring.
The current implemented “ideal sleep time” does not really help. It’s ok, if you fell asleep right after starting SaA, but who fells asleep this fast? 
For me sometimes it takes an hour or longer. The ideal sleep time so gets decremented by this delta, e.g 7h 30m - 60m is not really ideal anymore 
The new minimum sleep time feature could close this gap perfectly.