On Marathon, you can not build 1-turn Riflemen. The gold saving tactic is huge, it was also used by that person who won an OCC conquest on Deity. He piled up about 40,000 gold, built a lot of Samurai, then mass-upgraded them to Mech Infantry. Another benefit of building Maces and upgrading them is that Maces can get CR III right from the start with enough settled GGs, and a CR III Rifleman (after the upgrade) is unparalleled. The beauty is that with an Industrious leader and Stone you can pile up a lot of gold simply by building unfinished wonders that you don't want and waiting for the AI to complete them. Ka-Ching!