There is a difference between something being required and something being beneficial.
During hours of darkness sugars that are stored up in roots are processed for plant growth. During daylight hours the light rays taken in by the leaves are diverted for numerous tasks, including storing energy for use during hours of darkness, and a lesser percentage of total light taken in during daylight hours goes for growth than the percentage of stored energy that is used for growth during hours of darkness. Plants use their stored energy during hours of darkness much more efficiently for growth than they use light rays taken in during hours of light.
Periods of light and dark are part of a natural cycle for plants, something that is in their genetic code and something they expect." Altering that goes against what they want to do naturally and is against what they are genetically coded to do.
I have know people who run a 24/0 light cycle and they say they do get faster vegging but in the end they are talking about shortening the vegging time by a few days at the most. The cost of running your lights the additional time more than offsets the small possible gain.
If some dramatic timesaving would happen that allowed someone to add another grow or two a year it, especially if they were growing for profit, it would be worth doing but that is just not the case.
As it is using a 24/0 light cycle forces plants to grow in an unnatural condition where they are not growing at their overall maximum efficiency in relation to light provided and also power consumption and it is making them work against their genetic coding.
What small positive benefits that might possibly be the result of using a 24/0 light cycle are more than offset by the negatives of using a 24/0 light cycle.
Something else to consider is that plants can only absorb/process so much light. That will of course increase very slightly with each days additional growth but there will always be a limit to how much light even a full grown plant can absorb and process and anything above and beyond that is wasted light and wasted energy and increased heat and longer periods of heat.
Consider the following. The reason tropical marijuana is more powerful than northern strains is because of the difference in the time required to trigger flowering, as well as the difference in the photoperiod. The difference in the maximum summer light available and the minimum flowering period.
It is clear that plants that grow closest to the equator have the highest concentrations of THC. Close to the equator, the longest "summer" days are approximately 13 hours, while the minimum "winter" sunlight was still 11 hours. Plants from these areas contain far greater concentrations of THC than the high latitude varieties, where the summers are 15-18 hours and the winters only six to nine hours, depending on latitude.
Northern outdoor grown pot is big and looks good, but it doesn't come close to equatorials like Jamaican tropical Lamb's Bread in its stoniness. Commercial sinsemilla is also inferior. It also looks great and smells delicious, but it just doesn't have the same kick. The long days of the high latitude summers are detrimental to THC production.
Connoisseurs should give their plants no more than what keeps them from flowering 14 hours of light and cut it back to 11 hours during flowering for the best kick-ass sinse you can possibly get.
Personally I in part disagree with the last line and do not believe that going as long as 18 hours is detrimental to plant growth. I use an 11 hour night myself during flowering but I do not see the additional 4 hours during vegging as harming anything but the above is what is considered to be optimal according to what is natural for plants and what best matches their genetic coding and allows them to grow in the way they most want to grow and are most comfortable while growing.
The very best thing a grower can do is to attempt to duplicate the maximum optimal outdoors conditions in an indoor environment and that of course includes hours of darkness.
That is not something that is only an opinion. That comes from four family members with botany degrees and decades of experience on my part added in plus research.
