I'm not contesting your logic, but to make my mages crawl on the map seems to me quite long. If you organize your search wisely, you need one turn to move and one turn to search,whereas a mage casting search spells search every turn.
It is true it costs me a big quantity of gems.
I think that the more sites you put as a setting, the more it is viable to cast search.(the less gems it represents of your total income)
In facts, I guess it is just sheer lazyness.(cast monthly and forget..)
