Actually, I use my CF cards exactly like film on shoots, with the exception that I don't keep them for later.
I carry 38GB worth of CF cards in varying sizes and a few brands (mostly Sandisk, 512MB to 4GB). I treat each card like a roll of film because I found I tended to overshoot with larger cards, on some shots. Major shots, I'll start with a 2 or 4GB card, smaller, I'll start with a 512MB or 1GB.
The difference is that each shot (I shoot a lot of catalog) is offloaded to a digital wallet-type device in the field as soon as I'm done. The shot cards are seperated from the unshot cards. The end of the day, the digital wallet is offloaded, backedup and renamed to another external drive. That way, at any one time, I usually have two backups (cards and digital wallet or digital wallet and additional pocket drive).
As one poster mentioned, if you continaully use new cards, you may get a dud sooner than later. On my most recent shoot, I had technical glitches galor. In one day, I had a 2GB ATP card go bad, followed up by a failed Hyperdrive. (Also, had a bad Delkin 2GB UDMA which was V-E-R-Y S-L-O-O-O-O-W.) For the first time in years, I did loose some frames, because the ATP card was immediately unreadable after shooting and pulling out of the camera. By offloading immediately (or trying) my assistant was able to let me know immediately that we had problems. However, I had six more gigs on the shot, so really didn't need to shoot more. By and large, my redundancy has protected me from loses, especially by treating each card as a roll of film and not reformatting till the following day.