How do you know which lightbulb is which?

I think I've heard this before, but I'm not sure. I know that you have to flip the switch and leave it for like 10 minutes, then flip the next and leave it, and so forth. Turn them off and go into the next room and either check the after glow, or feel for heat on the light bulbs and use that as a measure to determine which lightbulb is which, as you put it.