I recently switched to Daddario, playing around 2 or 3 hours a day, they last 2 maybe 3 weeks before they really start getting nasty. I really have to be vigilent wiping the high strings off when I'm done playing, otherwise I get the dreaded sharp, grey color high strings. I have been using both NYXLs and regular XLs. I prefer the NYXLs but stocked up on a bunch of XLs for a pretty good deal.