Dratsab: Gillete Mach 3, shower, soap. Only adds a short amount of time to the shower.
I've found I can get through a week on one blade set quite comfortably and can stretch it out to two weeks, but things are getting a bit rough by then. Might have a crack at redjet's suggestion.
And that's is exactly what I was doing when I was using the Mach 3... then I found that Gillette had been screwing me. I bought a Schick Quattro because it was very cheap (on special) and I was being a tight arse not wanting to pay full price for Mach 3 blades. I get weeks (up to a month) out of each blade set! So the Quattro intro pack (which only had 2 sets of blades in it) lasted me nearly 2 months!!! Ever since I have felt extremely ripped off by Gillette and have been kicking myself for not trying Schick sooner.
It did take a couple of days (and it was only a couple of days) for my face to get use to the different razor, plus I think it gives me a better shave than the Mach 3 ever did.