you should hope it doesn't get that high,
I would only expect that with high detailed displacement maps, even then proggies with that in are able to put it back down to its original poly count
.
But poly reducers and other 'clean-up' tools are useful for the quick little bits, I use iron, its a tool that does its favours, but I could live with out it by working manually...saying that, there is quite a lot you can do manually...but some of it isn't quite worth the time. But poly reducer's probaly jumble up some of the geometry.