You guys are talking about different things.
Credit utilization of 0% doesn't mean paying your cards off on time every month so you avoid interest. It means paying your cards off before the statement period even closes so nothing is reported to the credit agencies.
I do this. All my cards have a statement period ending on the 19th or 20th. Around the 17th every month I pre-pay so my statement is $0 on every card.
When I use a card after doing this and the charge goes through before the statement closes, my FICO score goes up (vantage doesn't seem to do this).
For the last 18 months or so my FICO has been going up 22 points every time there is at least a little balance to report and down 22 points every time my credit utilization is 0.0%.
Seriously, I'd like to know too. I've always thought that you got them and then you were done. But maybe that was counting on there not being a bunch of disease vectors walking around.