Excellent, Mr. Rickbee
Since you seem to appreciate how accelerated skills development works---that the path of MOST resistance in the short term has the biggest payoff long term---here's another challenge.
It's tough. VERY tough. But I absolutely, positively guarantee you will be able to make truly excellent stems in record time (meaning both calendar-sooner, and elapsed-shop-time faster) after completing this one "exercise."
"Exercise" is in quotes because it's actually a full-on, comprehensive, self-contained course in stem shaping.
Cut off a 6" or so length of 1"-1.25" diameter vulcanite rod. Then, using whatever pipemaking tools and techniques that come to mind---meaning experiment your ass off until you find what works---
shape the rod until it's perfectly, evenly octagonal in cross section over its entire length, and
finish until it's as shiny as glass. Each facet the same width as the others, and all plane breaks laser-straight and razor sharp.
Like so:
It will exercise and test everything imaginable. Everything you've got. Ingenuity, tool adaptation, clamping methods, measurement methods, hand-eye coordination, sanding techniques, polishing techniques, making guidelines, following guidelines, and on and on. In short, do this, and stem shaping will forever be your bitch. You will understand everything you need to ever know about how to handle the material. Know what tool to reach for to achieve a certain result, and how to use it.
The "course" is inexpensive. Six inches of 1" diameter stock costs only $10 or so, and if you shrink it with restarts to where an octagon is no longer reasonable/possible, shift to a hexagon.
BONU$: Besides being able to make top-shelf stems in record time, you'll save the not-inconsiderable money that OJT pipe makers lose from unrecoverable errors (wasted time and scrapped material) their first few years.
UFOs must be real. There's no other explanation for cats.