Irregular light schedule.

I’d stay at 18 going to 24 for a boost for a few days isn’t likely to help as much as it could hurt or even set them back having to adjust, If anything turn your light power up a bit or lower the height a bit for more intensity while on 18h 👍 happy growin

You take chances with plants herming Switching light schedules or intensity of light can cause plants to do weird things.

Firstly, your plants require a night cycle. Folks every now and then claim that 24 hour cycles are a thing but in reality the plant is stressed to the extreme. I myself have done 24 hour light cycles (not intentionally). Other than requiring a night cycle, the plant also has a rhythm. For example, you can have a set cycle then change the light schedule and still measure nutrient transport analogous to the night-time happening during what WAS the night time. AKA, yes swapping around will harm your plant. How much harm is the question.. Past that, there is no optimal day versus night time (evidenced by the plethora of longitudes and latitudes which the plant is native to). This is plant speciifc, phenotype speciifc, and can completely be changed based on DLI target.

Hi, I wouldn't do it that way. You can download an app called "Photone" to calculate your DLI and then set your lamp to the ideal height/power. I use a light cycle of 20/4 until they go into flowering. Then I lower the hours to 18/6 until the end. I think they also need a phase of darkness to recover. And switching back and forth will probably just stress them out. And light stress isn't good either, as they might start to hermie. So, developing male flowers or other stress-related diseases or effects. Good luck!

Hi bud. This is a great question as many people often ponder this! But no, extra light will not do anything for your plant, if the daily light intake is already achieved. Same as with nutrients, the plant can only process so much. Hence more is not better. Hope this helps, even just a little.

If is auto you can give 24h light. It will finish faster than 18h. Good luck

The real question is what benefit do you think this provides? if you already provide 'max' dli relative to your environment, then this won't do anything useful. If it does help, it just means you need a stronger light that can properly provide light over a period of time that allows a sufficient dark cycle.