It would be useful to be able to update your availability for as an agent for each individual queue you are assigned to.
Use case example: we have rotating helpdesk coverage where not every agent is working the helpdesk every day. Some tickets need to be addressed as soon as possible and others can be addressed later. If we had a queue specifically for HelpDesk Agents and ASAP tickets were assigned to that queue by default, then agents could make themselves available to that queue only when they were assigned to work helpdesk and turn that availability off when not working the helpdesk. If they could adjust that availability on a per queue basis then even when not working the helpdesk they could still get less urgent tickets assigned via the round robin on the general queue.