Hey @Melanie58,
cool post and you are definitely not alone wondering about these things. I use to leave the cupboard open where I stored the spare toilet paper but learnt pretty quickly that was an expensive mistake.
I leave out 1 roll per bathroom per day of stay. So 4 guests staying for 3 days would have 6 rolls to use in my 2 bathroom apartment. I have found my Chinese guests will use a bit of every roll I leave out for some reason. European guests tend to use every millimetre, and locals seem to not use much at all.
Years ago when I started, I was much like @Susan990 following suggestions to upgrade, go premium etc. It's okay for Airbnb to suggest these things but they are not paying for the ammenities you supply. I now just buy the toilet paper bulk packs of 24 rolls and no one has complained or said anything. (I am not however using that nasty single ply stuff that feels more like waxy tissue paper)
This will sound weird, but try tearing off the first few squares when you put the toilet paper on the holder. My experience is when it's not brand new guests use less. If I put a brand new roll of paper towel in the kitchen, guests tend to use the whole roll in their 1 night stay. If I tear off a bit so it looks like it's being used, they tend to only use what they need. I have had the same experience with shampoo, conditioner, body wash, dishwashing liquid, soy sauce etc. If I put out a brand new bottle, 3/4 will be used. When I leave out half full bottles, guests only use what they actually need.
This might sound stingy, but when you go through the volume of ammenities I do, these things make a huge difference financially by the end of the year. Have a go and see if these suggestions make a difference to your guests usage patterns.
Brett