risk is mostly external, homes are rarely targeted
It is worth considering why this might be. Before committing themselves to a course of action that might turn out disastrously, it is much more difficult for a marauding gang to assess the fighting strength of the inhabitants of a structure (unless they manage to get a spy into the structure somehow) than to assess the fighting strength of a travelling party especially if the party is travelling on foot or exiting or entering a vehicle.
It is worth considering why this might be. Before committing themselves to a course of action that might turn out disastrously, it is much more difficult for a marauding gang to assess the fighting strength of the inhabitants of a structure (unless they manage to get a spy into the structure somehow) than to assess the fighting strength of a travelling party especially if the party is travelling on foot or exiting or entering a vehicle.