I went to 18”, pointy gansey needles because that was the conventional wisdom on what was used to knit fine ganseys, and I wanted very fine ganseys. It took me a long time to learn to make them really useful. Folks sold “gansey kits” of yarn and needles, but the long pointy needles are not useful without a knitting sheath that can be fastened over the right buttock. The physics are strongly against hand held “gansey” needles. And, long steel pointy needles have issues - I had to get bigger knitting bags to hold 18” knitting needles. I had to make point guards to keep them from sliding right through the fabric of my knitting bags. And, pointy needles cause more wear on knitting sheaths. On the other hand, the spring action of these needles driven in a vertical motion by the weight of my right hand, was the very fastest and easiest way I knew how to knit.
However, for the last few years, I have been making better knitting sheaths that can attach to a strong belt below the right elbow. These sheaths can comfortably take the stress of flexing the 3/32” spring steel that I like for knitting cold weather gear.
Now that I am using blunt needles, less needle motion is required, and I can get the required motion from 12” needles. The motion is still driven by the weight of my hand, so it is a very fast, low effort way of knitting. I use 6+1 needles for a gansey to fit my ample girth, so the weight of a set of needles remains the same, but they fit in a much smaller bag, and because they are blunt, I do not have to worry about them going through the bag. Overall, 18” needles are faster because there are fewer needle changes. With long needles, if you have some space to spread out without poking someone with your needles, you can use vertical or horizontal motions that change the working muscle, without changing the fabric (with practice). And, 18” US3 needles is the only way I know how to do good tight weatherproof Aran (10-ply/500 ypp) fabrics.
(If you are doing brioche stitch or lots of bobbles, stick with pointy needles and a not too splitty yarn.)
These days, I often use finer sock needles, so I can get almost the same motion from 9” needles, but the needles are soft enough to flex sideways (or vertically) with just the effort from the base of my thumb, opening up additional styles of knitting small objects. Since, I now use the same needle adapters for straight needles and swaving pricks, in a small knitting bag, I have the tools for a good variety of knitting styles that quickly produce good uniform knitting, for when I need to get a knit object finished quickly without over working one set of muscles/joints. If you are going to knit seriously, you need different knitting techniques that use different muscles, but which produce identical fabric. The shorter needles also allow knitting in the car or plane or boat. Long gansy needles (even blunt needles) are not well suited to knitting on public transportation.
One can make a good pair of fine, warm socks in a couple of days. If you can get someone else to drive, you can get much of the work done on the ride up to camp. And yes, I still think the motion of the longer needles is smoother. But swaving works very well even on rather rough roads.
In the old days, I often knit while walking and hiking – I saw the old pictures of people knitting as they walked and thought it was “cool”. After I discovered knitting sheaths and knitting belts, I found that knitting sheaths were not very good while walking, and I decided that hand-held needles could not produce the quality of knitting that I could make with knitting sheaths/knitting belts. Thus, I gave up on knitting-while-walking. If I am going to knit, I sit or stand in one place. Knitting with a knitting sheath while standing does work fairly well. In Jane Austin’s time (and before), women often had knitting sheaths in the form of jewelry stitched to the gowns they wore to social assemblies, so they could knit lace while they stood together and talked. The first time I went to the V&A, such knitting sheaths were only labeled as “jewelry”. It is worth noting that Jane Austin did not knit.