As the Consumer Reports folks said, "the three-step products did give the paint a deeper, richer appearance..."
But yes, to do a car properly, factoring in washing also, will take you about three hours. Whew!
Use three different applicators, and three different removal towels. Personally, I'm getting a nice orbital machine. I've had it with taking years off my rotator cuff every other month.
You should use about a quarter-sized (not two dimes and a nickel...bwahhaha...I crack myself up) dollop on the applicator for each panel. If it's a nice cotton terry applicator, that dollop will go farther and farther as it gets saturated. Back off of the application accordingly.
Here's how I work my car: roof, hood/lift gate/left side/right side. I do a complete three-step on each panel, just so that I can have that sense of accomplishment. Hey, it's psychological I know, so shaddap!
After I finish the whole car, I pull out my cotton towel that I call "softie," and buff the whole car, taking care to look for any wax residue. The nice thing about the Meguiar's stuff is that it dries clear, but it's good to get it off anyhow.
I imagine a clay bar will do the same thing as the paint cleaner, in case you're a man of the earth instead of chemicals.
They last...well, the three bottles that I have took me through two jobs on my Legacy GT, now two jobs on my WRX. There's still a lot left.
Good luck, and they work really well. The polish and wax come off really, really easy after you use the cleaner. I did my Legacy right before I traded it in, and that car looked fan-freakin' tastic.