If you’re ready to update to the latest El Capitan release, but hate amount of time it takes to download via the Mac App Store—and the fact that you don’t have an installer left behind to use on other Macs—then what you want are one of these two installers from Apple.
Combo Update: Updates any version of El Capitan, including the recent betas. I find this the most useful DMG to keep around.
Delta Update: Will only update El Capitan version 10.11.3 or the recent 10.11.4 betas. This will be the quickest download (though not by much).