Have you tried the approach you are suggesting? I faced the problem of looping (and/or creating temporary thing on the fly, without actually querying DB) through anything to check the availability an then display it to the customer. If the system was supposed to have fixed number of sessions per day - that could be done by the workflow with plenty of steps or by designing the page with many buttons/whatever representing bookable resources - but fixed number. Then just showing/not showing the ones, that correspond to the specific hours in the day. And lets not forget checking against already booked sessions on top of that…
But since schedules can be different - eg. Monday 10 sessions every 1h, Tuesday only 3 sessions, and Sunday 24h of sessions to book (just an example) - I can’t imagine using above solution… RG/nested RG? How to populate it by rows and columns representing days/hours/events/whatever if there is no existing Thing in DB and expression builder is limited?
I think that’s why people are asking how to populate the database with slots each time the “booking system” topic appears here - there seems to be a problem with displaying the schedule after in some easy and logical manner (i may be wrong).
How did you or how would you approach it?