Cant set a specific date - but my guess is 2 weeks. I have the feeling that they nefed something again. It used to be around equal chance if we got salt, exo, titan ore or granite in adventure loot. Now it seems as we get granite maybe one in 20 adventures done.
Our upgrading of buildings are on halt, we have sent Asterix and Obelix down the nile in hope of finding a solution on the problem. I have lot and lots of exo wood piling up - but no granite.
If BB did nerf this - please change it back or there is a bug - please fix it.
If you are experiencing the same thing - please confirm.