Charter Checkout is a crazy time. There will be a person walking you through the boat with a checklist, but you and they have very different goals.
They will show you anything to do with operating the boat and it will be like an information dump/overload if you haven’t done this before. I would suggest having at least 2 people do this walk-through with them. You will go over the operation of the boat from head to toe and they will ensure that all safety equipment is there.
You, on the other hand need to be ready for a week (or more) of continuous operation, and you don’t want to have to waste time making repairs or dealing with something which would detract you from your vacation.
This Link (The file came from someone on Travel Talk Online a few years ago) has some good ideas of what you might check before you leave. Certainly you should check all of the things that break down a lot. Toilets flushing and not leaking is a big deal. A smelly mess and one head down is not fun, so check it before you leave. We had a VHF radio that was TERRIBLE the last time we chartered. People could hear us, but the sound that came back was just garbled even though the other boat was just 200 feet away.
At the height of the bareboat charter season, quite often they turn the boat around in one day. I have no idea how they do it. Cleaning and repairs by just a few people for a fleet of boats sounds like mission impossible to me. During this time they may not be as thorough and you will have to catch the things that are important to you.