Keep them until they dry rot.
No, seriously, I had/have the same problem. I kept every magazine because there was "good stuff in them I might need". I gave all my QNL collection to a new quilter (and I had some of the first years) who now quilts rings around me. Others I bundled for yard sale or donation. If your stacks are more than a year old chances are you should let them go. New ideas come out and shove the old ones to the back of our minds making mental clutter.
My husband has the same problem
big time. He has to keep every publication. I packed a huge trunk with mags. from the 1950's forward, boxes and boxes and he has a row about three feet high along the wall. Magazines! Just magazines! And travel folders, restaurant info., souvenir booklets,
old catalogues......for cars, guns, lanterns, knives, tools, more cars, railroadiana....