I suspect night watering helped because it minimized evaporation and gave the girls time to drink more. Same for 4 gal a day.
I have 9 girls going and by 5 weeks they were drinking almost a gallon each, daily. Now I am in straight coco, in 3 gallon fabric pots, so I’m sure there’s a difference, but 2 gal for 16 seems like a very small amount. It may not even be getting to the lower roots since it’s in soil.
From the size of your pot’s do a little reading on here and see if more water, less frequent would work better for you. I grew in containers outside and only watered every 2 or 3 days. I let the soil tell me when to water.
You may even want to get a moisture meter / probe that sticks in the soil about 10"s or so with a needle display %. There not very accurate for the cheap ones but they will give you a reference.
Also, what’s your temps?
Ph of your water?
I did a search for " soil watering frequency "
This thread has some good info: