Usually my strings tell me when they need changing...like when the strings are so dead that no matter how much I tweak the tuning I can't get the guitar to sound in tune, then it's time for a string change. *BG*

I see all these advertisements for hand exercises to improve strength, speed, etc. Anybody had any experience with this? Any endorsements/recommendations/critiques? My tack is that these things will come through practice, but I'm open to suggestions.