Student house - one moving out, the rest are staying: how do you inspect for deposit return?

Tenancy Deposits

I wonder if anyone can advise? Thank you!

A house with five students - all except one of them is staying on, with a new one year tenancy agreement all signed. So one tenant is moving out and a new one moving in. Would you normally inspect just the room of the person moving out, or would the whole house be inspected in order for the deposit to be returned to the tenant who is leaving? The tenant who is moving out is worried that if a new tenant has moved into their room, they won't be showing their room in a way that will secure the return of their deposit - ie empty and in good order. The other tenants' deposits are aready retained from the previous year. 

Also, there is a three day gap between the end of the last tenancy, and the new one starting. Does this have any impact on landlord or students? Obviously, it's not worth them moving out for three days and then in again. But it's a situation I haven't come across before.