The classic mill spun gansey yarn has several virtues. It can be knit fairly loosely, (not too warm) and still have the stitch work that Pops! Or, it can be knit firmly to produce firm padding to protect the wearer in a hazardous environment (e.g., booms and spars being swung into sailors as the sail boat rolls).
The disadvantages of mill spun gansey yarn is that when it is knit tight enough to be be weatherproof, it lacks drape and becomes stiff like a board . If you need warm suit of armor, it is a good fabric, if you do not need armor, then other fabrics may be better.
I was very proud when, I first thought I could spin a good approximation of the mill spun gansey yarn. As I knit fabrics for different purposes, I understand that the mill spun gansey yarn is NOT likely not the best yarn for many for many purposes. And I found that I could spin a world of yarns, that mills could not spin, and some of those yarns have real virtues.
One thing I found, is that some of the yarns that do not look so nice in the skein, produce wonderful fabrics. The proof is always in the final fabric. (And the proof of the fabric is in the wearing!) Firm multi-plies with soft ply twist can produce weatherproof fabrics with a nice hand and great elasticity. Wearing such fabrics is like having a second skin.
I discovered thick an thin singles by mistake. I had a big bump of commercial fiber with a lanolin based spinning oil that started getting oxidized and sticky on one side of the bump, but I spun it, as it was, anyway. The single looked like crap, but the 5-ply knit up into a rather wonderful fabric. It is not in the books, It is the kind of thing that is only discovered by trying a lot of stuff that does not work, but keeping one's eyes open for stuff that does work. It was something that snuck up on me - the early singles from that bump were properly uniform, then I left the bump sitting for a few months, and when I came back, it spun as thick and thin. As 5-ply, the yarn still looked like crap, but it knit up into a fabric that I like a lot. Now, I have found other ways to produce a thick and single without trying to age a bump of commercial fiber.
The thins give the fabric hand, and the thicks tend to full and bond the yarn together. However, the net effect is different from simply plying singles of different grist and twist together. Over all, the yarn is much softer than the mill spun gansey yarn, so stitches do not pop, and it is more difficult to knit into firm padding (e.g., boards). On the other hand, it is much easier to knit into a very warm, very elastic fabric that is as comfortable as a second skin. The thins give it luster and durability, the thicks give softness. The fabric has almost the feel of a fabric knit from woolen spun.
I have a kilo of 5-ply sport weight from such thick and thin singles, in a bin, ready to be knit on #0 needles. Also in the bin are a pile of swatches of various fabrics knit from the yarn, Twist in the singles varies from about 7 to 9 tpi, but it is 5-ply and it averages out into very competent singles. All singles are continuously tested for competence (tensile strength) as they are plied. Ply twist is much less than standard, so the yarn is soft and stitches do not pop as much as with mill spun, but on the other hand, the plies spread to fill gaps and needle holes resulting in a fabric that is warmer any you can get from mill spun gansey yarn, and the fabric has a reasonable drape. The yarn is aggressively washed and steam blocked prior to going into the knitting bin.
All in all, it is a reminder to respect the materials and the process, and not to get caught up in imitating mill spun. Handspun can have intrinsic virtues that are not in mill spun. We CAN make yarns that mills cannot. And, some of those yarns are very, very nice, not because they are different, but because they have virtues. We have forgotten some of these virtues because mills cannot produce such yarns. Wassit was hand spun 5-ply. This last bin of hand spun 5-ply gives me new respect for what 5-ply hand spun can be.
I like the hand. I like the fill. I like the warmth. I like the stretch and elasticity. I like the durability. I have been spinning it from 60 count long wool with good luster. Soon, I will be back to spinning Rambouillet from Ann Harvey up in Calpine. Then, fabric from fine wool has less durability and luster and is much softer. And, of course the Rambouillet is white, not ecru. Still the drape, fill, warmth, stretch and elasticity are all there.
All in all, I figure about 6 hours for a hank of worsted sport weight, 5-ply. Worsted 2-ply at that grist has a poor drape, so a 2-ply would have to be woolen spun. It takes me about 3 hours to spin 560 yards of 2-ply sport weight, woolen spun yarn. So the worsted 5-ply takes about twice as long as woolen 2-ply. That is, I can spin the 5-ply worsted for a sweater in 24 hours and the 2-ply woolen in only 12 hours. However, I am going to spend some 90 hours knitting a fine sweater. That 90 hours makes it worthwhile to invest the extra 12 hours for the extra drape, fill, warmth, stretch, and elasticity of 5-ply. If I do not want the warmth, then I go up a couple of needle sizes and I have a faster knit sweater that still has drape, stretch, and elasticity.
Wassit was popular and inexpensive. It was popular because it was good stuff. It was inexpensive because a lot of it was produced. I stared looking at 5-ply because it was warm and durable for fisherman's sweaters. I keep looking at it because I like the "hand" of the fabric.