changing the light cycle

ive been busy with finals approaching and got lax with my plants, since their hydro they basically maintain themselves... and now harvest time snuck up on me...this is my first grow, i heard i was supposed to drop the light to under 12 hours for the last few days of flowering...

how detrimental is not dropping the light cycle to the potency of the bud? i could probably hold off harvest a few days if i wanted

It's hard to prove it makes any difference. I wouldn't worry about it.