For shorter stays, we do not change the linen - but generally for longer stays, we change the linen and towels every 4 days.
We have several apartments in a single block. We have fixed keyboxes outside, with each numbered and having a different code.
We send the details to the guest prior to arrival so they can check-in without someone meeting them. It works well for us as most of our guests are travelling longer distances. Some people arrive late at night, so this works well.
I run 4 apartments but used to run larger hotels so the laundry and ironing issues had to be resolved!
The key to easier & faster ironing is all about how you fold your linen! If folded correctly, the ironing takes only a little time and it looks great. I now use fitted sheets and have learned to fold them that makes the ironing straightforward - here is a link to show how to fold them:
I do not fold my sheets in half but into thirds: once you have folded the edges in an have a long rectangular shape, fold one side into the centre then the other side over that. It makes a neat rectangle and you can then place that into your steam press.
It takes a little practice but it doesn't take long to get skilled at it. I currently iron all mine by hand and it doesn't take too long. Also I have found that ironing the folds of the sheet gives reassurance to guests as to the care taken of the linen - they like to see that it is all clean & ironed.