Hasch
learning and laughing
If it's a regular grow bag with woven or spun fabric then there will be water evaporation through the sides.I use the 5gallon fabric grow bag.
In my experience letting it dry out (or worse dry out for a few days) will hinder the plant + the microbial life to develop and thrive.
I also decide when to water by lifting the bags. But I try to keep them moist all the time, avoid letting them dry out.
My plants seem happy that way