In my last 10 years of Shop teaching, I was forced to adapt my Tech.Drawing skills to include CAD. The old story - the best way to improve your skills is to teach it to students. (They seem to find the most difficult questions to ask.)
I cut my teeth on IMSI TurboCAD (very popular with many Australian High Schools) from Ver.3 to now Ver.16.
In retirement, I am mainly occupied with designing and constructing one-off custom
items of furniture for family and friends.
I would be poorer for the lack of a CAD program. With it, I can make my mistakes on the computer first, and when satisfied, print out a 3D graphic for clients to evaluate.
Furthermore, the program takes the guesswork out of some many (otherwise) mathematical calculations -eg. today, I needed to space slats of different widths along the ends of a cot. I drew it up on the program, printed off the spacing full size and used it to directly mark on the timber. Fitted perfectly!
As a bonus, it provides a perfect excuse to interrupt the monotony of repetitive machining.