2 votesMichael commented
Most people will not need appointments scheduled at 5:47a or 9:03a. It's just odd. Maybe there should be an on/off option for custom timeslots. Workers specify their first and last possible meeting times and set a default occurrence of minutes for all timeslots.
Timeslots show as a dropdown menu which shows only desired times and saves time when making appointments on a phone or tablet
While setting an appointment, a user picks a date. Base only needs to look for a matching date. If the date is found, hide all the timeslots that match (conflict)
The result is a beautiful selection dropdown menu that (for sure) contains only unused times.