That's pretty much been my experience as well. I can't stand wearing my Korkers (either pair), but put them on due to necessity after close calls due to what you describe above. If it has been really dry for several days, and the roof hasn't been oiled in years, I'll walk a shake roof without them under about 6/12, otherwise, I put them on no matter what. If a roof is as bad as in the pictures posted, I won't walk most of it, because they will crack, and because it's pointless. That applies to comp. shingles as well.....