I vary my detailing on how into the real car the model represents I am. I make a decision on each model on the level of detail I will and what will be working or not. I am not anywhere near as obsessive as Bill, but do find myself trying to correct a model to reflect the 1:1. To me, form, fit and finish are primary. The amount of detail you add does nothing to correct those. Also, how one displays the model can also impact detail. If it won't be visible, do it if you want (you'll know) or let it slide. There also is a point where detail detracts. Try to do all the wiring and plumbing in an engine bay in 1/25 scale and you'll see what I mean. Sometimes you back off to stress the more important parts. But, do what you enjoy. I have a friend who, for years, would do the body mods and get it in primer and stop. That was the part of model building that most interested him. Eventually he did get a couple through to completion, but the design and fabrication are where he got his most enjoyment.