24 hours in veg or 18/6?

I'm growing for the third time and I've read about growers who keep their plants in a grow room with the lights on 24 hours a day during veg. Is there an advantage to the 18/6 cycle? Will plants grow faster with 24 hours of daylight?

I just recently decided I was going to switch to 24 hour lighting also during the veg phase. From what I have read it is beneficial I.E. grows faster since it is growing all day, apparently plants don't require a dark period during the veg phase. It sounds like it is one of the bonuses of growing indoors might as well take advantage! I don't want to mislead you though I have just read a bunch of websites and forums, nothing truly scientific.