For growing autos I've had best success at 20 hours of light. 16 hours indoors doesnt even really meet indoor photoperiod veg standards. I found plants under 20 hour light cycles finished a touch faster with notable increase to yield. Plants on 24 light never got better than the 20 hour plants but suffered ailments at a higher frequency. They need lights off hours. I'd say ur best bet is change to 20 hours