As I've told everyone who will listen (including some people--Kevin--who barely care) over the past couple of days, I put in the designer-recommended lifeline on row 287 of the Mystery Stole, and I'm never going to put in another lifeline!
For those of you who aren't knitting the stole (and why not? All the cool kids are doing it!), the designer sent out an announcement a couple of weeks ago that said we should all put in a lifeline (that's where you run a smooth thread/yarn/piece of dental floss through every stitch in a row you know is right, so you won't lose any stitches if you need to rip back to that point) in row 287. Even if that would interrupt the pattern of where we'd been placing lifelines. Even if we'd never used a lifeline before (that would be me). Just do it, and we'll thank her later.
So I did, and it was kind of a pain in the neck to knit the next row, and for the first time in my life I nearly knit stitches together with each other accidentally, and I'm not doing it again (unless, I suppose, the next clue tells me to just do it and I'll thank her later...).
The good news is that it gives me a better answer (it's a pain, and makes me make mistakes!) when people see I don't have any lifelines in my lace and ask why. (People, as though I'm constantly running into strangers who want to discuss lace with me, but never mind.) My old answer (knock on wood, but I don't usually make mistakes that are big enough that I can't correct them without significant ripping) was just asking for trouble. Falling back on laziness and refusal to carry around extra supplies is much safer.