So generally I have wholeheartedly embraced going the right side of Progress first. In generally the extra worker, food, gold, and science I find give you a better jump start than the prod and culture bonuses on the left. That said, there are exceptions for everything, and I wanted to highlight one here. Spoiler : So ultimately there are two factors that made me go left side in this particular game. 1) Limited Land Resources: This is a common scenario with certain sea resource focused starts. As you can see, most of my early tiles are going to be sea focused, with a push towards work boats over workers. The land around me doesn't have much need for worker improvement in the very early game. So I would rather have the prod bonus for faster work boats and to balance out this more food heavy start. 2) "Donated" Workers from Korea: This was less common but put me over the top in my decision making. Korea decided that having 2 workers (it took progress 2 for the free worker) by its capital with a warrior off a few tiles drinking with barbs was a good idea. So in 1 turn I bagged 2 workers and a farm pillage for my trouble. Now honestly I probably would have gone left side on number 1 alone, but with the two donated workers from Korea it sealed the deal.