In the throwaway world of train and light hiking shoes, I can't recall replacing a pair of laces the past several years. The metal hardware on my old school leather boots, my primary "tires," do a pretty good number on the laces, though. I go through a pair roughly annually. I recently replaced a pair of kevlar laces that lasted well, except that the ends were shredded.
this time, i bought lengths of thin round webbing, cut into lace-sized pieces. they are a little slippery new so I have to double-knot, but I don't know why I didn't think of this before. they should last for years.
thoughts about laces?