From the publishers website:
The Dungeons & Dragons 4E rest system is built for campaigns where the characters delve through a dungeon, one encounter-filled room at a time, taking short rests between each one, until they reach the final room-encounter, and complete the dungeon. Now, the system isn’t broken, and it creates a certain type of experience, but if you’re running a different type of campaign, you need a different type of rest system. Rugged Adventures presents a system where players feel worn down after almost every fight, until they rest for the night. One encounter per day (or fewer!) will be all you’ll need to offer your players to make sure they’re being challenged. And all of this is achievable with just a few small changes to the rest system, with little or no impact to the remaining mechanics of the game.