I've always been a "pick everyday" kind of person (though, I don't have any good rationale for it, just what I was taught as a kid). However, I remember reading a thread like this a couple of years ago, and wondered if my mare would ride any differently if I backed off on picking and only did it every couple of days.
Wouldn't you know it, the first time I tried leaving her feet without picking for a couple of days, she moved out terribly on our first ride. And when I picked her feet afterwards, she had a giant, sharp rock wedged deep in her foot- could have been there a couple of days, who knows. Poor thing. I know the odds of that happening again are probably highly unlikely, but it was enough to put me back on the "pick everyday" team.