Creating a new ruleset version for each team ensures that each team's work is isolated within a specific version, preventing overlap and conflict. Setting up a branch ruleset for each team further isolates development work, allowing parallel development streams that can later be merged back into the main application ruleset.
These two options, when used together, provide the most flexibility for teams working on separate enhancements with uncertain release dates. References: Pega Platform Help - Branch Rulesets.