I find having this in my menu bar handy, because I naturally glance at it from time to time. If I'm on battery and not performing some intensive task and I see the number being over 1000, I know that something is wrong. I then look for offending apps to close. Usually it's the web browser, and I've done something like loaded every gif on a reddit page then forgotten about it and have it hanging back with 20 other tabs on some chrome window in the background, but it's chewing the hell out of the CPU and sometimes RAM too. I then close that, the number goes back down, and I get on with life without destroyed battery life.