It's not a ploy at all... honestly!
The bulbs have 100 hours of life, but once that time is up, the bulbs will look like they are still working away, but the output would certainly not be the same!
The thing I hated about all of my other UV lamps was that I never knew when to replace my bulbs and unless I kept a note of when I changed them, then the only way I had of knowing they needed to be replaced was my clients would have problems with their nails... not a good way to find out now is it?
So CND have done all the hard work for us and have made the CND lamp with the built in timer, to help us... not to fool us!
Where would we all be if we reset the timer each time it went off?... we'd be back to not knowing when to replace our bulbs and we would have a lot of very unhappy clients and in turn would lose money... now that really doesn't make good business sense does it?
Stick to doing things the right way and you won't go wrong... if you reset the timer when the bulbs have gone you are only fooling yourself and your unsuspecting clients.