Five gallons is big enough. Five gallons is about the smallest size pot that should be used for cannabis. I use seven gallon fabric pots and sometimes use five gallon fabric pots as well, but anything smaller than that the roots are going to become bound.

It's not surprising the roots were dangling down because cannabis likes to shoot its tap root down deep and long, and the fact that you had long dangling roots means those plants are loving the soil and water they are getting.

The plant I'm growing in a seven gallon fabric pot is five feet tall and she started busting roots through the fabric pot at the start of flowering and she's been continuing to try to shoot new roots through still. The roots end up dying and shriveling off where they shoot out, but ultimately that tells me my monster plants would like an even bigger pot 😅