Where I spend my days ($WORK), we have multiple monitoring systems for just about every service on every server that we have. Many of these are Nagios, some are built in, and others are SiteScope. All of the systems generate email alerts that either go to our pagers, our email, or both. From time to time, management would ask a question like “How many pages do you get in a week on average”, which up till a couple of months ago, our answer was always “It just depends”.