The Adblock Plus blog details the thundering herd problems they faced. Their ad blocking lists checked for updates every 5 days. Eventually, many users' update schedules would converge on Mondays because office computers did not run over the weekend. Updates that had been scheduled for Saturday or Sunday would spill over to Monday.
Windows does much the same thing w.r.t. policy refresh (which sucks down files from domain controllers) and update of "occasionally updated" metadata like last logon timestamp.
https://adblockplus.org/blog/downloading-a-file-regularly-ho...