Here’s a photo of the sweater sleeve when I started to repair my threadbare knit sweater

I outlined the bare patch using a Frixion eraseable pen. Starting at the “bottom” right, I created a row of stitches, then turned the sweater 180° and worked my way back. I shifted the edge position to stay more or less within my markings.

As you can see, it’s possible to create an interesting, wandering pattern to repair just the threadbare spots. For this repair I used a sort of matching variegated sock yarn (fingerweight) which I had in my stash.

EastLondonKnit gives a good description for how to do Swiss Darnning: https://eastlondonknit.wordpress.com/2014/04/21/swiss-darning-tutorial/ [If this link doesn’t work, click here: https://jmncreativeendeavours.ca/wp-content/uploads/2024/01/swiss-darning.pdf]

You can also use Swiss Darning to create “appliqué” on a knit garment as well (I don’t have any examples that I’ve done but I’ve got a sweater that does that].

If you can’t figure out how to do Swiss Darning on your own, Flora Collingwood-Norris can show you how (and she has supplies for doing the work, as well). https://www.collingwoodnorrisdesign.com/visible-mending/zoom-workshop-swiss-darning?rq=swiss%20darning