Yep, we all have tricks that help us get the general idea and a lot of drawings seem to come from the USA and therefore imperial rules.
Here in OZ we are metric BUT if I am coming out of a bank for example, there are often markings on the exit 4,5,6,etc with sub marks indicating the 6" bit. My guess is that most still think of a person's height in feet and a half?
Suppose that will fade with younger generations, who knows?
Something else I needed to get my head around is Third Angle Projection (think that's what it is) as I grew up with Plan, Front, Right or Left Elevations where the view was as if you walked around the part or building.
Until a fellow model engineering club member said to imagine the part in a salad bowl. Looking straight down you see the plan. Slide the part to the right or left and as it slides up the bowl you see the respective view. Similarly sliding the part up the front or rear gives those views.
I was a textile dyer by trade so this modeling caper took me back to my Tech Drawing classes at secondary school. Amazingly I still remembered lots of it.
Hope my above waffle makes sense and helps some.