i veg under 24, they havent seemed to care, then i switched to a larger light, only real benefit or difference IVE (important emphasis there) noticed is, my electric bill is a little lower from the 5 hours its off now, plants still look the same tho.
i veg all my seedlings under 24 hour.
i just have a milk crate with a few bare bulbs above it, no timer just on in a closet,