In most organizations, many departments could conceivably be run "lean" - ie with the minimum number of staff needed to complete everyday routine tasks - without catastrophic consequences.
In any organization operating mechanically complex facilities in a cold climate, operations is not one of those departments.
Why? While routine operations tasks are important, operations' most crucial role is to respond to malfunctions/failures and mitigate the potential damage from those failures.
If you only have enough operations staff to just barely handle the routine/everyday stuff, you're going to be screwed when the crap really hits the fan (which it eventually will).
See, that mitigation role is vital - halting a failure cascade before it becomes disastrous. If you don't have enough trained, competent staff present to delay/halt the failure cascade... it can turn into a chain reaction of exponentially-escalating damage and disruption.
@IrelandTorin tell that to all the c level execs where I work who refuse to take staffing seriously for the last few years because we're "working fine as is right now" while they ignore the massive levels of burnout right under their noses.
@Hobyrim In other cases, you may have your full complement onsite at the time but the number of simultaneous emergencies is simply too many for them to cope with...
Running with bare-minimum staff in a critical technical department is like having a single line of defense with a bunch of holes in it... and making matters worse, new holes continuously form faster than they're patched.
It's just a matter of time until disaster occurs.
Tick... tick... tick... tick...
@Hobyrim If I've learned anything from my time in industry so far, it's that C-level execs and beancounters are cut from the same cloth, and that neither of the above truly understands how dire the consequences could be if understaffing results in an inability to properly operate/maintain mission-critical systems... or stop a single sufficiently severe failure cascade.
In some cases, it may only take one or two people being sick on the wrong day to wreak nigh-unimaginable havoc.