When operating shared accommodation, it's common for people to come and go frequently, so ensuring you have a well oiled check-out process will help you ensure you reduce your void periods, so what can you do?
Pre check-out inspection
This should be carried out roughly one week prior to the tenant moving out and this will ensure you can inspect the room and schedule any maintenance. You can also prepare your cleaning team as to the current state of the room, so they know how long they're going to need to prepare the room for the new tenant.
Offer an incentive for referrals
Offering an incentive to all your tenants to get you referrals is a win-win situation as you get good tenants and don't have to worry as much about constantly finding new tenants
Ask your tenant to find a replacements
Your tenant may have a friend or work colleague that needs accommodation, so ask them to find a replacement for their room. They may know a lot of people, which makes your job a lot easier as you can invite 2 or three along for a viewing and chances are one of them will want the room.
Ask for a review :)
If you've been providing great service and looked after your tenant there should be no reason why they won't be willing to leave you a glowing five-star review on Google.
Return deposits promptly
If you have taken a deposit, return it promptly as your tenant may have to have paid another deposit to move on elsewhere. If you need to make deductions for damages then make sure you have sufficient evidence to prove it, before and after photos are always a good idea. Ensuring your rooms are always in as new condition before any new tenants move in will remove the "oh, that was already there" excuse.