The company I work for has a requirement to provide 24/7/365 coverage for many of its products, and it tries to do so with only three people to cover the particular product to which I'm assigned. Up until a few months ago, they were doing it with just two people.
Every other place I've worked has had a minimum of four people to provide round-the-clock coverage, so they can split coverage up into shifts, and no one needs to be woken up to respond to a call.
I'd assumed that the four-person minimum was a sort of IT industry standard, and argued for it at my current position, but is that really the case, or was I just spoiled by the excess people at my previous jobs? Is there any standard way for determining minimum manning based on required coverage?
Some extra detail: The number of calls/tickets we get is very uneven. Sometimes, we'll go a week without getting a fresh ticket, and will focus on other duties. Other times, the calls are nonstop, and I've personally run into situations where I'll get a call just as I fall asleep at night...then get another call as soon as I finish the first one, and I'll be left with zero sleep before the start of work the following day. These calls can usually be handled from home, but sometimes they require a drive back to the office. The argument against the need for extra people usually centers around the quiet periods.