@Nigel263 there are two issues here.
If, like us, you clean yourself then you may not want to spend every day cleaning and changing the listing over. This is how we feel so we have a minimum 3 nights stay.
If however it is financial viability that is important then just add a cleaning fee that properly reflects the time and/or cost of the changeover. Many people use these as a self correcting mechanism to avoid short stays. For longer stays it will amortise over the higher number of nights and you will still get longer stay bookings.