No, 20 hours on and 4 off are good for the autos. You could do 24 hours on but I think the plants need a bit of darkness to rest too.

The plant does different things at night such as taking in oxygen instead of CO2.

The oxygen is necessary to break down the glucose. So you could say that the plant eats at night.

Also, I read that plants such as the banana plant put energy into the fruit at night. So bananas grow at night... But plants are different, I think weed grows day and night

Also, a lot of root development is believed to happen during the night time hours.

I think whatever goes on at night would be necessary for full health so give it at least 4 hours of darkness.