The most common mistake we see in Obs is a house with a heavily secured front door and a back door that would open with a firm shoulder. It is understandable — the front is what you look at every day and what visitors see — but on a terrace with a service lane behind it, the front door is the route nobody would choose. Rebalancing that is usually inexpensive and immediately effective.
Concretely, that means a proper lock in a properly fixed frame on the rear door, a yard gate that cannot be reached over and released from the lane, and hinge bolts on anything opening outward. Where the yard is overlooked only by the lane, it is also worth thinking about what is stored in it, because a bicycle in an unlocked yard is a stronger reason to enter a property than anything inside the house.
For landlords, the structural answer is a restricted key profile. In a house let by the room, keys are cut for partners, replaced after losses and passed between tenants across years, and no amount of asking will produce an accurate count. On a restricted profile every copy has to come through the landlord, which converts a permanently unknown number into a countable one without changing anything for the people living there.