I'm working on the back of the cardigan and I have two lifelines, which are the white pieces of yarn. I can alternate them as I finish each section. If I make a mistake, then I only have to pull out the yarn to the lifeline and not all the way to the border.
https://b.convo.casa/media_attachments/files/112/921/994/546/561/784/original/31f83e88f9c2b692.jpg