I think the designers saw the problem to a degree - which is why if a levy got wiped the province dropped a level, but they didn't build in a cap on the maximum number of units you can raise.

To get that to really work you would need to track the actual population and a subset thereof being the number of potential warriors (i.e. surplus young men). That would have added to complexity badly - remember this is before we all had computers and the like to track this sort of stuff.

I'd suggest that you need to put an annual cap on raising units aside from mercenaries, possibly a longer period for slow breeding races. Or if you use the province growth rules recently posted by Evan Sørgjerd's (http://www.birthright.net/brwiki/ind...rovince_Growth) and 'use up' some of the growth points in a province when you raise troops so putting an automatic cap on the number that can be raised without reducing the province level.