Thanks for your feedback.
Questing is giving the player a goal. Game achievements... for example an achievement for production shut down due energy consumption getting bigger than production. That sort of thing is pointless. Almost all achievements are more a "social thing" "hey, look who got the PVP DPS achievement". But I digress.
Downtime doesn't look great as a metric for efficiency (not in this game context). My HUB biomass burners are silent since I got coal. Sometimes I rebuild my factory or its "modules" getting some closed. Also, I like to plan and an entire "module": A miner, 16x smelters, 32 constructors, etc and power up everything at once. That can be horrible at your metric.
Maybe a good metric can be, in the context of this game, how many clicks you accumulated at the workbench at each unlock recipes time. Less clicks meaning more automation, meaning more effectivity.