I use flat diamond stones for most of my sharpening. They cut reasonably quickly and stay flat. No oil needed.

You have to remove metal to really re-sharpen. Hones re-shape the edge, but eventually you have to remove some metal. It takes a little practice to get accurate and consistent, but it isn't too hard. Always watch the point, it is easy to round off the point.

The various guided sharpeners make it much easier, but those are not cheap.

Does Randall have a shop specified sharpening angle? Does it vary by knife model. And, if anyone knows and can answer, please say whether you mean an inclusive angle (the angle formed by the two bevels) or an exclusive angle (the angle between the bevel and an imaginery center line).

I believe the paperwork that comes with a Randall specifies the angle.
They recommend 20 degrees.
I'd say use a white ceramic rod and the a steel hone rod rather than removing material that the diamond would unless the edge is really poor. Just my $0.02!

I guess I'm not smart enough to answer that question, but I sharpen at 17-20 degrees and do not use diamond sharpeners...(although)...a diamond "EZE-Lap" sharpening steel comes in the tube pouch and on my longer (4 5/8") Stanaback Special..."BUT"...it is intended for a quick and convenient touch-up method in the field & not as a steady diet.
Hope this helps,
Capt. Chris

For a long time I used a Norton bench set almost identical to the ones used in the RMK shop, they have a metal base mine is plastic. Nowadays I highly recommend Work Sharp products as they are extremely effective and very reasonable. Many products like the field sharpener are available locally.

I also use the 3-stone Randall, shop-preferred, Norton rig! Most excellent!
Stay Sharp,
Capt. Chris