At the expense of being 'shot at' by the local sharpshooters, I personally find it hard to believe that anyone can make a decent furled leader in five minutes---from starting the layout to completing booth Shorb loops; or even using a tippet ring in lieu of one Shorb loop.
I use a powered (motorized) board, which twists and furls at the same time; drastically reducing the time required for these processes. I am using the standard 'rope laying' technique. To use the typical leader furling methodology, which you have done an excellent job of describing, you can only speed the process up by going to a motorized system, as far as I know. With such a system, you would twist both legs at the same time, and then switch the butt loops to a third hook, which spins in reverse to the other two, at which time you would 'furl' the two together. Once this is accomplished, you would hang the leader to, in the words of Skip Shorb, my mentor, "let it relax". Doing it this way eliminates having to "...unclamp the '"tip end"' [and] let the two '"legs"' spin together."; which could save a little time.
Beyond this, I have no idea how you can improve both the 'speed' with which you make one, or it's overall quality.
Motorizing is a simple, and inexpensive thing to do. Many of us use a sewing machine motor as the 'driver'. You need three gears, one of which is the driving gear, and the other two are planetary gears. Each will require a hook, the two planetary gears are for twisting, and the 'driver 'gear for the furling hook.
There are many here who canhelp with the specifics, if you are interested; including myself.
Cheers!