I have just finished fixing a flat, the sixth one I've had in this inner tube since I installed it on July 16 of this year. The weird thing is, this hole went right through a previous patch, only two inches from another previous patch that also went right though another previous patch. I know, you would assume I'm not taking the glass/nail/staple out of the tire; but that's not the case. Each puncture is from a new cause.

My commute adds up to 80 miles / week. Here are the relevant maintenance records:

July 6: New tire: Schwalbe Marathon with kevlar puncture protection.
July 16: New tube (Schwalbe); old instant patch (I hate those things) had failed, and that tube had lots of patches already.
July 20, flat tire: puncture on inner side of tube (rim strip problem? Never found any reason for it). I patched it.
July 23, flat tire: tube inexplicably blew through the side wall on the way to work. I patched the tube.
September 8, flat tire, puncture near valve; I patched the tube. The tire was tearing around the July 23 puncture, so I replaced the tire, adding a Slime Liner. The new tire is another Schwalbe Marathon with kevlar puncture protection.
Sept 21, puncture, a 1/2" steel staple on the way home from work. I patched the hole, which was 2" from the Sept. 8 puncture.
October13, flat, tire went flat over night, never found the cause of the puncture. I patched the hole, which was right through the patch over the Sept. 8 puncture.
December 15, tire went flat after I got to work. Cannot find the cause. I patched the hole, which was right through the Sept. 21 puncture.