What is the role of Permission Set Groups and how do they improve permission management at scale?

Permission Set Groups (PSG) allow you to combine multiple Permission Sets into a single assignable group. Instead of assigning 5–10 individual permission sets to each user of a given persona, you assign one PSG that bundles them all.

Benefits:
- Simplified assignment: Assign one PSG instead of multiple individual permission sets per user.
- Muting Permission Sets: A PSG can include a Muting Permission Set — a special PS that removes permissions from the group without modifying the underlying permission sets. Useful for edge cases (e.g., a Power User PSG that grants broad access, with specific permissions muted for certain regulated roles).
- Scalable persona management: As permissions change, update the PSG; all assigned users are automatically affected.

Architectural best practice: Define PSGs per user persona (Sales Rep, Sales Manager, Service Agent, System Admin). Use muting permission sets for compliance edge cases. Avoid modifying profiles — the "Permission-Set-Everywhere" Salesforce strategy will eventually deprecate most Profile settings in favour of PSGs.