I had it for two years, had it removed in march 2025. I wasn't aware it was off for three weeks, as I turned it off when in Europe and exiting through two Xray machines for screening. When I discovered it was off, I turned it back on for another 2-3 weeks, and there was no difference.
My neurosurgeon said it works for 50% of the population. He told me I gave it more than "a college try".