Heel length,,just a few .000" long as A/S states.
Getting the angle correct (tool lift) has much to do with keeping the back side from plowing up your cut on the turns.
A longer heel and lower angle to it can be very useful for cutting the long straight border lines. The fact that the back side of the tool is riding in the cut already made is what is helping keep the line straight. Try and turn with that tool and it will tear up the cut.
A short heel of nothing more than a few .000" in length is plenty strong for cutting steel.
Using a fixture and power hone now as I've been cutting w/ carbide for many years,,I sharpen most everything the same way now.
I sharpen the face of the tool with the hone running.
Then turn it OFF and put the heel on the tool by just setting the edge on the hone (while in the fixture and and adjusted to the right angle) and turning the hone disc by hand perhaps a 1/4 turn altogether,,with gentle hand pressure on the tool.
That's more than enough to put a heel on the tool.
It doesn't take much..you don't want very much..
I may change the angles for the material being cut,,but the sharpening technique stays the same.
I also 'blunt' the sharp point especially on carbide when working on extremely hard alloys.
Something you most likely don't get in to here. But it works on HS tools as well that have a hard time keeping their edge on some steels. Older cast and wrought iron can be tough on the point.
You'd think it would negate any cutting action but instead it strengthens the point and prolongs cutting life of it.
The shorter the heel the easier it is to keep from gouging up the cut as you turn with the back edge of the tool,,and the higher the tool is lifted/held (heel angle) while working is the other half of the trick to keep the cuts nice and clean.
But there's a limit to the heel angle where you start to loose efficiency in the edge of the tool. Too high a lift and you can't get a nice cutting angle on the edge.
It's a balancing act and every engraver has a favorite chisel,,grasp on the tool handle, and angle on the bit. You just have to experiment with in the fuzzy borders of what is too much and too little when it comes to the angles and lengths regarding tool sharpening techniques.