Don Foreman wrote:

(...)

AutoCAD did indeed have a very steep learning curve. But once the
keyboard commands are learned, it is incredibly fast to use for a
competent typist.

Yup. Remembering all the command mnemonics was impossible for me.

I once saw an experienced operator "build" a small
commercial building (in 3D) in about 10 minutes. He didn't use the
mouse much! His 3D model included HVAC, plumbing, wiring, doors,
windows, and a walkthru. That was with a DX486-66 with maybe 512 meg
of RAM. I think it might have been about circa R12 or R14.

Whoa!

I still like and use ACAD (R14) fairly regularly, but if I wasn't
facile with it I'm sure I wouldn't invest the time to learn it now.

The thought makes my head hurt.

--Winston