Ah wow... I thought the randomization is a bug.
Thank you for your answer, now I have to beat my own record while waiting for a battleship like multiplayer. :)
I am playing this game for years now and my record is 122 turns.
But I can not figure out the best way to get workshop. Sometimes I get the upgrade after tech level 8, sometimes it comes later. Sometimes it comes before the "warriors stronger" update, sometimes after...
Is it just random? Does it depend on the population size as well?
And what is difference with the timber and rock islands?