Yes, there is even an Apple Support article that says that.
Does anybody know WHY that would happen? Do the re-formatted tracks somehow save a lower density signal? Normally, whatever is written to a magnetic medium (format or data) remains pretty stable. Even if some of the previous formatting (eg part of DOS 1.4mb tracks) is still present on the disk medium, why would it work a few times and then fail?
I'll be trying the bulk-erase method to see if I get better performance. I don't mind how many times I write the floppies, so long as I can get usable boot disks while I wait to get hold of some proper double-density disks.
Rick