I echo the sentiments around here. Anyone with a decently operational brain won't go for the granite pit. The gold mine, even if it's lvl 6, would realistically only give you about an extra 15 ore/h. (12 minutes and change cycle with a 3x buff). 90 extra gold ore for the entire duration of the buff if you use a badge. The "excess" won't even be able to pay for the buff itself really... the benefit would be so minuscule that the vast majority wouldn't even think about it. As far as granite goes... just play the TO wisely and you'll never really have to do adventures to get whatever granite you need, even more so during special events. I made about 40k granite from this last event alone, and I'm far from being the best trader out there.
That being said I'll reiterate one point that has been mentioned time and again but to which the devs remain completely silent as usual: why can't we just build any amount of troops we want? Why foist gem-sinks on us that no one - with a brain - would spend even a measly one, while you can enhance the gameplay and incite the player to get a premium since it'd become dastadly easy to make troops? And why oh why, don't you devs come out and say why haven't you implemented it yet with a half-decent answer?