From my point of you, production corresponds to the amount spent in building queues, so if on one turn you spend say 10000 fl., you might reach #1 on the graphs, whereas if you spend nothing or next to nothing next turn ( due to lack of funds or building queues being already full), you will fall to the bottom rank...

IMHO it has no disadvantage whatsoever, and is a just a way to see where you stand compared to other factions...

the turn settings should have no implication on the calculations as I play several campaigns simultaneously in 0.5 and vanilla and production seems to work exactyly the same either way...