You are gonna get all kinds of answers. You will hear the chest pounding of those who only stop every 25 miles blah blah. Dude, there are really no rules. You need to do what you feel like and what you want to do.
This is one area that I have no shame. If I think I need to or want to rest, I rest. I don't set a goal that i won't rest until I get to any point. I just stop. May be 5 miles, 10 miles, may be 1 mile. That decision is up to no one but me.