You can learn the BASICS of ACAD in a few days, but ACAD is designed by engineers FOR engineers!
Without as solid formation as an Engineer, Draftsman, Architect, Civil Engineer and/or similar, ACAD is just a toy.
ACAD is probably the most powerful Engineering tool on the market, but it will NOT make you an engineer. It took a good 7 years full time tuition to become an engineer.
The drawings made by "non-engineers" are totally useless in real life, and cannot be used to "make" things: too many errors!
Think of it this way:
You can design a house (easy). But HOW are you going to calculate the depth of the foundations? That, ACAD cannot tell you.
You can design the track of a tank: pretty! But how are you going to give the workshop the detailed drawings to MAKE the parts of the tracks? The worker needs something he can work from! You can "design" the track, but can the worker MAKE it?
I can design parts in ACAD tha cannot be manufactured, or even exist in real life...
(think of a cube of steel - one piece - with a spherical hole in the middle! You can DRAW it, but you can't MAKE it!)
I am an Engineer, and I work with ACAD since the mid sixties, where it came to the market (in DOS :-)! ) It took me a while to master it.
I now have the lastest version.
I am still learning it...