Lets just say I grew up learning to become an architect, when I was young hand drawn blueprints was everything. Then along came autocad and I learned and loved it as well. Then along came RTCW I got hooked and I learned how to map for games. Was a easy transition for me because it is the same premise without rules. I don’t have to worry about weight, materials, tolerances or integrity’s etc.
When it comes to level design there are many approaches depending on the type of game and gameplay you are shooting for so I would not say that there is any one design fits all approach. About the only thing that remains consistent for me is the planning. I always in advance lay out my level on paper or paint and understand how I am going to fit everything together in my head long before I lay a single brush. Top and Side View Minimum so I can see the 3D depth. Its much faster to change something with a pencil and eraser then in a level half fleshed.
As far as over detailing it which is what I think you where really asking. Using actual blueprints as reference is just fine. I wouldn’t try to do a 1:1 translation for most environments but again this all depends. If I was doing a game that only involved a couple rooms then I would pack as much detail as I could into those rooms. But if I am making a city block I am going to give just enough detail to make each area believable and move on so there is no lag etc. Something else you will find is that just because you add more to something doesn’t mean you actually adding more to it. A 1:1 translation may translate to a horrible environment to move around in depending on the game again. Bumping into things getting clipped or blocked.
However again using real life anything such as blueprints for reference is wonderful and suggested. The key term though I believe is “reference”.