I’ve bravely/foolishly carried on without life lines.
a. I’m lazy
b. I worry that evidence of the lifeline can be seen after it’s been removed.
However, I would advise to do as I say, not as I do. I can’t guarantee a problem free run without a lifeline. I’m just taking a risk. I’ll probably use lifelines for the sleeves, as I’m using the top lace pattern for the whole length of the sleeves, and that’s the stitch pattern which caused me to swear whilst knitting the back. That was just a short stint for the back and front, but the sleeves are a whole different story. That stitch pattern is actually very easy, but accidentally dropping a stitch or two off the needles can change your demeanour very quickly.