0 penalty 做法 too simple too naive too nice lol

1. move out date may not line up with move in date. In this case, you can argue current tenants will pay to the day new tenants move in.  

2. cleaning. Hard to argue it is not clean enough after current tenants move out. Typically there could be carpet shampooing and/or normal deep cleaning needed. 

3. time/cost to advertise, screen tenants. If possible I would like to meet probable tenants to get a feel of people. In this owner can estimate the time she spent getting current tenants.