I personally as a general rule of thumb consider the following when modeling in a production.
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you have to hit a mark in a short amount of time to prove the concept in 3D
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your model needs to get pushed through a pipeline
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revisions will be made!
So I will block out the character and take it to a medium level of detail, then re-mesh, and continue sculpting. Once that looks ok, you can further tune the edge flow.
Considering that the poly count is totally dependent on the production, I tend to work with a base mesh that has enough to deform nicely but still low such as 5,000 to 10,000 polys.
I model completely in quads, this will serve you well if you need to add or remove edge loops. Also it renders well in mental ray and for games it triangulates, however once your model is complete you could re-mesh using tris if it is a requirement of the engine, but i personally would not start with tris.
The highest level I take models to is around 4 mil, although with HD geometry you can go higher. Simply because once you start to go over a couple of mil the details become so fine that a texture would serve the purpose better. Having said that, with careful shell placement (spilting up your model, the sky is the limit, even then each subtool would be around 4 mil if needed)
Lastly, I have seen highend film production models and they can be insanely high, meaning that most of the detail is in the model and not a map…having said that consider that you want to keep a nice silouete on your model.
So I would suggest you model from a base made of quads which will allow you to subdivide to around 4 mil with 6 subdivs.
long story short…its up to your better judgement
hope that helps