The SLA time should always be configured considering the actual business / working hours. In the scenario given, which is 8 working hours per day, the SLA rule should be configured with the tolerance interval 16 hours which amounts to 2 working days. Always configure the SLA time considering the working hours the customers are in.
For e…g, if the SLA time to be configured as 5 days (considering 8 working hours per day, it is 40 hours), then SLA time in the rule should be configured as 2 days and 2 hours (which amounts to 40 hours i.e., 2*24 hrs + 2 hrs)