Many production applications need 24*7 support. So how many resources do we need to support an application round the clock? The below simple calculation can help -
Assume each resource works for 40 hours in a week.
In one week, you have to cover 24*7 = 168 hours / week.
So total FTE = 168/40 = 4.2 FTE
To accommodate for vacation and sick leave, we can round it to 5 FTEs for 24*7 support.
The typical shift timings are - 7am-4pm, 3pm-12 midnight, 11pm-8am, This ensures that there is a 1-hour overlap between each shift.