What does the flag Shift bookings - System by default is set as shift base. Please tick this option if you need shift bookings as per "shift time" instead of "Shift type" do?

-If this flag is ON then shifts will be checked based on Shift time
For example - A member can't be booked in the same shift time start time & end time, can't be overlapped

-If this flag is OFF that means the shifts will only be checked based on Shift type
For example  - If a member is booked in AM shift type then it can't be booked again in AM shift type on that date.