I don't really follow this logic; if you only move to a new driver when you 'need to', why is having a guarenteed new driver every month great? Surely the optimal solution would be a new driver every day, then you'd always be guarenteed a bang up to date driver rather than one that is up to 30 days old. Or even a 'random' frequency like Nvidia use shouldn't be inherently worse than a monthly cycle, because by your own admission you are only looking to update your drivers on a 'random' schedule anyway.
Well, I like the AMD's cycle of releasing new drivers.
For the enthusiasts there are at least two or three drivers a month to try out (a preview, a beta and an official release). We get hotfixes the very same or next day if anything goes wrong.
Crossfire users don't have to wait for driver updates to fix scaling issues in games - CAP can be installed over the top iirc and don't require a restart so you get them straight away - their really small too.
With every release there is a change log and Rage3d and Guru3d have quite comprehensive drivers subforums where new releases are being discussed and tested.
There are modded drivers for mobile GPU's users.
If you're looking for a stable system, you can install every second or third official release and should not encounter any problems. For those looking for even the slightest performance improvements or quick fixes, it is ideal to have them asap.
Look at the 5800 series cards, they gained so much performance with the drivers that 6900 series is barely an improvement.
I very rarely encounter drivers problems, don't really upgrade Nvidia drivers too often on the secondary PC and both my desktop and the laptop use ATI GPU's and haven't really had a single issue that would not be related to overclocking or third party software for ages now.
Sorry for hijacking the thread, Nvidia owners. Off I go.