Well, this is a little something I've found that I will share with you people.
This is my way of saving ALOT of time.
What you need to do is angle your camera so it is above your head, then use Z or C to strafe, you can strafe down a 89 degree wall like that, as long as its not 90 degree, you'll just walk down the wall.
This can also be used to walk sideways on a wall, you can go down or sideways, I know you can go up sometimes, I'm just not quite sure yet how to do it. I'll edit my post later.