Currently gangs will sit in a base with several members uncontested (you'll see this a lot on era as well) because they have so many people it can be very hard for gangs with less members to base. This can be mostly attributed to the way gang points system functions, there's no incentive for gangs to try and take multiple bases to spread their members out. My suggestion to fix this would be to limit the amount of members of a gang that can be in a base at one time, this would stop gangs from piling members in a base to accumulate gang points.