more often in the future, as manufacturers continue the battle against piracy. Although, as you say, the number of times you format your drive is your affair, 5 times is probably far more than the average. I certainly haven't formatted a single drive more than twice. I can't remember this point cropping up before with Norton, which may be an indication that very few people have met with the same situation.
Irritating as it may be this is something that's here to stay, and the protection afforded by the software for most people is worth more than the irritation that will be experienced by the very few who format as often as you.