This is true, but some would say the gains are negligible. You also want to take into account the kind of light(and wattage) you're running. If you're running under 100W of CFL's you don't have to worry about huge electric bills. I'm running a 600W HID, so I'm very concerned about my electric bill. I'm about a month in and I've been running 18/6 from day one. I'll be switching to 12/12 sometime this week. Next grow I plan to run some CFL's for the first few weeks.