Steam will update games only in the selected period and not otherwise. It is possible to disable that in the Steam settings so that downloads continue while games are being played. Recent versions of Steam block automatic downloads of updates or game files when a game is started.
When the bandwidth is required for other operations.When game updates are known to introduce issues or unwanted changes.To avoid that bandwidth is wasted when games are updated that you don't plan to play in the near future.There are several reasons for wanting to be in control:
While that is the desirable option for most users, as game updates may introduce bug fixes, new features, performance improvements, and other beneficial changes, some Steam users may prefer to be in control of the updating process. If there is a network connection when you start Steam or Steam is running, updates will be installed if available. Valve's Steam platform client will update any installed game or application automatically by default.