My guess is it's less about the duration and more about the consequences. If our VPN was down a week we might not switch because we have an alternate workflow,

My guess is it's less about the duration and more about the consequences. If our VPN was down a week we might not switch because we have an alternate workflow, but if our production servers were down for a few hours we'd switch. Also, I missed one really important email and that's all it took to switch the hosting for that.