How to prevent sleep while installing lots of updates?
There an app developed to deal with that issue, Smart Timeout Keep Screen On by guidology available from Google Play Store:


  Smart Timeout allows you to specify apps that will keep the screen / display on. Once there are no specified apps visible on the screen the normal screen timeout is enabled.
  Works great while reading articles in web browsers, email, or any app you specify. You'll no longer need to worry about touching the screen to prevent the screen from sleeping, dimming or timing out.


 

Ain't free, costs 0,76€, but "saves" you from the described annoying situation :)