Imagine you work at the rest stop on 90 Westbound after exit 3, and you miss the exit for the rest stop. That means you have to drive 30 more miles to the next exit, turn around and get on 90 Eastbound, drive about 50 miles to exit 3, turn around again, get back on 90 Westbound, and drive 20 miles to your rest stop, trying not to miss your exit again. 100 miles out of your way!!
And then what if you miss it yet again!
And then what if you miss it yet again!