Most of them were for a line check/fed ride (some were for captains upgrades that just needed another hour or two to hit 50). But your post made it sound like it's rare. It's less likely than losing a full trip but it's not rare. I had one trip a couple months ago where I lost three separate turns in one trip.

ALSO, it may be a single turn for Dmaxvelo18 but that turn may be a part of a four day for the LCA so when training is looking for a four day to give to a student, there goes Dmaxvelo18's turn.

That said, I don't look at it as unfortunate. Getting paid to not work is great. ;-)