I use Astroglide, and no matter how much I use, I find that the best feel occurs only in the first 2 minutes. After 5 minutes, it still feels great, but I start to miss the incredible feeling of that first 2 minutes. So I reapply the lube and continue. I usually end up doing this about 6 times for the entire 30 minutes. And I MUST feel that peak lube quality during my orgasm. If I really wanted to save money, I could go the entire 30 minutes without re-lubing, but to get the best 30 minutes in my life I don't mind spending 6 times the cost.
What about the rest of you? Please name your lube and the number of minutes that the peak intensity lasts for.