I started doing the first wedge (dart?) on the waistband of a pair of chinos. I cut the wedge twice, as I didn't leave enough excess to fold back on the first one. I pinned it and tacked it to one side, then halfway through stitching proper, I realised I had threaded the needle with regular sewing thread, instead of the jeans thread I'd bought for the job.
So I ended up (almost) stitching again down that same line with the same thread. I left the general purpose thread in, and offset the jeans thread to it very slightly. After that, I pinned the wedge in place to do the other side, but my eyes got tired, and stomach started growling, so I broke off for a while. As I sat there eating a Cumberland sausage and fried egg butty, I decided food like this is worth having to let a waistband out a bit...
I might pick it back up again later, even if it's only to run a tack line through. I would like to try to get one side complete though, if my eyes are up to the task.