Did 6 Bandit's Nest in total and didn't drop granite, gave up a few days ago as the remaining requirements weren't possible to do in a few days even if I dropped it on my 7th try.

In the form it was presented I would have to give it a sideways thumb. It's not terrible but not great, very resource hungry but also forced me switch my map up so I can do more adventuring so in the long run that's not a bad thing, worth a try but the random factor(s) being so restrictive meant that the attractiveness of the final reward diminished with each failure to get lucky. Switch out the "Get X granite from a specific adventure" for either "Complete adventure Y losing less than X {troop type}" or "Get X granite from adventures" so you're reducing the overly prominent luck element and I would give it a thumbs up.