I have self serve key safe access to my 2 apartments.
Most guests like the privacy of self serve access which suits me too, saving time waiting for late comers.
However I have discovered guests really appreciate you just popping in before dark to introduce yourself, reassure them, answer any questions they may have.
From my perspective I want to check they have parked their vehicle in correct place, are respectful to other guests, have the correct number of guests, understanding the house rules etc especially cleaning the kitchen, taking out rubbish on departure.
I usually receive great reviews when they have met the owner of the property
If the guests are not there when i just pop in I ALWAYS send a text message to confirm all is ok with their checkin and if they have any problems I am ALWAYS available to contact by mobile