There are many assumptions made by non-knitters about the knitting of an afghan. I don't know many knitters who have knit afghans and, of those, I don't think I know many who liked knitting afghans. Myself, I hate knitting them. Why is this?
Non-knitters think afghans are easy to knit. Theoretically, yes they are. In reality, they are mind-numbing lay tedious and put a tremendous physical strain in the wrists, hands, and elbows.
Non-knitters think that an afghan is a "quick knit". An Aran cabled sweater is a quick knit compared to an afghan. Even if the needles are US 15 and the yarn is bulky, there are often so many stitches in a single row that it could take an hour to knit an inch. Just ask me.
Non-knitters think that afghans use a relatively small amount of yarn compared to a more intricate pattern, like a fair isle sweater. An afghan is usually somewhere in the neighbourhood of 4 feet wide by 5 or 6 feet long. That's like knitting a linebacker. Pause to think about that for a minute; then, try to calculate how much yarn it would take to knit a linebacker.
So it's been five weeks and I'm sitting here knitting on this custom order afghan, still. By the time I'm finished, I will have knit 1.7 miles (yes, MILES) of bulky weight yarn. By my calculations, I've knit just under a mile so far, which leaves me nearly a mile more to knit. I'm also going to need physical therapy.
I can say with absolute certainty that I will not be knitting another afghan in the near future. Maybe not again in this decade.