My grandma wrote down on her pattern how long it took her to knit a row on the blanket. She recorded one time for a back row, which is just knit and purl stitches, and a second time for the front row, which takes longer because of the cables.

So I timed myself doing a back row, and was pleasantly surprised that I did it in 10 minutes. Perhaps my knitting is not as abysmally slow as I feared. Or Grandma did her times on a larger blanket. Hm.