How do I calculate quota for other activities?

Other activities are regular booked activities that don't belong to a capacity category for the selected capacity area. Other activities can be repeating activities (such as lunch breaks) or bulk activities (such as meetings) or shift activities (that are automatically created for different working-time patterns in your org). The Max available and Quota values for repeating, bulk, and shift activities aren't updated immediately because such activities are recalculated periodically.

The minutes used to estimate other activities when service SLA window starts/ends with a given hour:

If an activity has a service/SLA window end value within a given hour, the system tries to use all the remaining minutes from the "window end" till the end of this hour.
If an activity has a service/SLA window start value within a given hour, the number or minutes that can be used in this hour is calculated so as to not exceed the time remaining from the "window start" till the end of this hour.

The ‘Other activities’ parameter is used in the following calculation:

Maximum capacity - Other activities = Activities that can be booked within this time slot

The calculated value includes the activities that:

Are not part of the capacity management
Belongs to the other time slots

The algorithm performs the following actions for the selected capacity time slot and activity:

It determines the interval of the working hours (including overnight) affected by the capacity time slot. The interval is equal to the value used for calculating the maximum capacity.
On the other hand, the algorithm calculates the expected used capacity of an activity for a particular hour is assumed to have started within such hour. The result of this step is the expected used capacity calculated on an hourly basis.
The resulting Other activities value is calculated as the sum of the expected used capacity values for the hours affected by this time slot.
If working day is started within a given hour, the number minutes that can be used within this hour is calculated to not exceed the time remaining from the "start" value till the end of the given hour.
If working day is ended within a given hour, the system tries to use all the remaining minutes from the "end" value till the end of the given hour.