I guess I'm one of those good cases. It took me forever to find a pain medication that worked. It only took one try for a depression medications, though. I've been on both for... 8 years or so now? No signs of them no longer working. On the other hand, if I'm off the depression med for 3 days or longer, it's noticeable. The longest I was off it was 6 months when I was out of work and couldn't afford it. The pain med I can go longer without, but problems get cumulative until I'm in constant pain.