The Prefectures are enough-))
the costs for wyverns aren't that high in terms of price-to-quantity..
it's easier to recover gold and resources with wyverns, which can then be used to build the municipality..
on max difficulty, when you start from 0, there is even little or no wood and ore; building the municipality depends on clearing the area as quickly as possible..building a market, guild, smithy, and then finding another 5000....sorry - I don't want to wait that long-)))
It is certainly desirable to build up wyverns in the first week, but on max difficulty, there may be problems with wood. So whether you like it or not, you'll have to fight with gnolls