Well, I can't say how long they will last.... but, using floppies back in the day to transfer pics between a PC and my Amiga, I might have a disk fail in 2 DAYS. I have read that part of this has to do with Windows, I dk, tho...
What I can say, is the times I have gotten the 'seek error' message, it turned out to be a faulty disk... and you HAVE cleaned your drives recently, right?

*I cleaned my 1200T's floppy drives last night*