Hi Ray, I use 11 x 1, 12 x 1 or a 13 x 1 size threads, and by using 4 threads on the barrel or section and only gripping with two threads in the Cap, the Cap is removed and replaced in 2 complete turns, No one i have shown these pens to, including so called Pen people have not noticed its a single start thread, and said nothing about how long or how meny turns it takes to remove or put the cap back on. One advantage is if you have a grain match the cap always goes back on in the same place giving the match every time.
PS. I was also told it is more very difficult to produce good clean 3 start threads by hand. I do not know if this is true as I have not tried it myself.