I'm not an expert on drawing those things and I'd definitely be interested in hearing what techniques others have come up with, but my assumption is that since it's all drawing and these are things that you can do digitally, that they all have similar techniques to how it's traditionally done.
Which is to say they probably just have enough knowledge of perspective and hand eye coordination. Stencils, rulers, and masks are also commonly used and all those are available via shift clicked lines, the line and shape tools, selection tool, and masking/pixel locked layers. The only thing that is different is that it's just another medium, but the logic and thought process to those techniques are largely the same. You just might find different tools that get you to those places in a different way.
This is a point I often make to people but I feel like it worth driving home every time. Drawing does require development of hand eye coordination, that much is true, but you are really drawing with your brain. These concepts you are tackling can and have already been applied to hand drawn/painted traditional work and the principle remains the same. This is even true in 3d sculpting and modelling, there are concepts that are applicable no matter what program you are using.
So one thing to ask yourself is whether or not you understand these things as well as you think you do as you are trying to translate them digitally. What are some parallels you can make from this program to how you think it would be traditionally done? Because someone had to be drawing these things well before digital art became possible or widely used. And one parallel we can make right off the bat is that they often heavily utilize an understanding of perspective and masking.
There are multiple ways to approach drawings. I have seen artists draw mechanical things digitally in all the methods you've guessed, the only consistency is that they all are using a similar logic when they are using those techniques.