There are different type of visa as per different requirement
VISA AT EMBASSY: 5-7 working days depending on the embassy location. For example, it takes only 24 hours to get a visa in Cambodia while it may take 5 working days to obtain one in the USA.
VISA ON ARRIVAL: 3 working days to receive the approval letter by email. However, some agencies can handle it in just 2.5 hours in Emergency cases.
EVISA: It takes 3 working days to receive the evisa code but many users reported it actually takes 5 working days.