Appointments that run 50 min (e.g. coaching, counseling, teaching) or 1h 20 min (e.g. classes run by professors, teachers, coaches, creatives) are common but the services setup only offers prefixed durations.
Therefore it is not realistic to use this platform unless the company changes all their service durations and/or pricing.
Also enable customized durations for buffer time
Customize the price of services or extra. In this moment I use a low price and give the possibility to upgrade step by step for ex. 50€ plus € 25 plus 25€
There is a workaround for now, and that is to change the default time slot step before setting the service duration, then change it back to how you want the clients to view the options i.e. change it to 15 minutes, set the service of 1h 45 with a 15 minute buffer time. After that set the default time slot to whatever you want.