I've never had an issue creating reasonable time clocks if you need a week to recover. I try to do pacing similar to books like The Dresden Files. Everything is going fine and then it all goes to heck in a handbrake for a few days.I really don't understand why people assume that the world is static...
okay and none of that changes the 5mwd... unless that McGuffin is all or nothing game breaking....
There are so many ways to accomplish this, usually it's as simple as your enemies continuing to pursue their goals without waiting until it's convenient for the PCs.