Doubt regarding how "Begin check-in before shift start time (in minutes)" works in Shift Type

so I set “Begin check-in before shift start time (in minutes)” as 60 and “Allow check-out after shift end time (in minutes)” as 60 that means that employee can check-in 60 min before check-in time and 60 min after check-out time

Screenshot from 2025-02-16 12-23-48

but if employee check-ins before 90 min of check-in time or works late and checks-out 90 min after check-out time then how attendance is marked?
and also what if I added 0 in both these fields then employee can check-in and check-out at any time?

i am thinking that this is added for strict check-in and check-out so that employee can only check-in and check-out in a specific time interval.