As a salon owner, I unfortunately have to deal with the problem that my clients make many appointments in advance, but then don't keep them all. This is where a waiting list for another client's preferred appointment would come in handy.
This way, the gap could quickly be filled with someone on the waiting list.
One client can put himself into several days on the waiting list
Procedure:
Client 1 cancels
Client 2 has put himself on the waiting list for this day and the service fits into the gap.
Client 2 receives a text message that he/she can now use a space that has become available.