Hi Nikola, Here is the context: The worker receives one person per appointment, the working hours are spread out from 9h00 to 12h00. Let\\\'s imagine that the appointment from 11:00 a.m. to 12:00 p.m. is already booked, if another person wants to book from 10:00 a.m. to 12:00 p.m. this is not possible since the worker already has an appointment from 11:00 a.m. to 12:00 p.m.So far so good ! Now if I modify the \\\"slot step\\\" from 120 min to 60 min, then it is possible to book an appointment from 10:00 a.m. to 12:00 p.m. when there is already an appointment from 11:00 a.m. to 12:00 p.m. That\\\'s a buggy behavior, isn\\\'t it ?