Yes. I actually find it really difficult to stop thinking about the implementation (and the usability) of what I'm creating. These are good things to be concerned about, but not when the problem is already too complex.

On another aspect of it: the last couple of days, I've found it very effective to think of a model as just the nouns, not verbs; data structures, not algorithms (as in the Brooks quote). Guess this is implicit in the idea of a constraint, but it's helping.

The other thing is that the model doesn't have to be precisely correct. It only needs to be correct in the important ways (if I don't already know what the important aspects are, a complicated model probably won't enlighten me). This gives me conceptual framework to think in, rather than to be an authoritative definitive description, perfectly correct in every minor details (they can be corrected early or late, if they really are minor). I find it helps to give me a vantage point, to see further. My mind is very fertile with finding solutions - provided I can see where I am.