For a settled family home, the honest advice here is almost never about the front door. It is about the side path that has become invisible behind a hedge, the kitchen door that still has its original hardware, and the garage pedestrian door that has been unlockable for years without anyone treating it as urgent. Those three, done properly, change a property far more than a new front cylinder.
For a house taking in lodgers, the priority is structural rather than physical. Who holds a key, what does it open, and how is it withdrawn when somebody leaves? A designed hierarchy — front door and own room for each occupant, common parts for whoever manages the house — settles that permanently, and it makes the annual changeover a routine act rather than an anxious one.
The one thing both households benefit from is a written record. Very few long-settled homes here can say what the keys in the kitchen drawer open, and very few lodging houses can say how many front-door keys exist. Producing that register costs almost nothing and it is what makes every later decision straightforward instead of speculative.