You can go with Houston's method or, you can work from one end to the other. The last 5 to 10 feet you measure the width of shingle exposure and "cheat" them so that you end up with a normal sized shingle at the end.
Even if I were using Houston's method, I would still measure for an even exposure. I do the same thing while laying the shingles up the slope, the last 5 to 10 courses are measured so that I end with full width lap/exposures all the way to the ridge, the ridge being equal to the rest of the slope exposures, rather than having a 2" strip along the ridge.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!