Why have my new neighbours have not moved in yet?

[Noseynoo]

Id love to know a list of reasons as to why someone would not move straight in to their new property.
Old neighbours left around midday and I'm interested to know what reasons there would be for them not moving in at the usual completion time?
So far I have thought of...
Something wrong with funds
First time buyer living at home so no need to move straight away (wouldn't you still come and look at it though to make sure everything ok)
Needs renovation (I dont think there is anything urgent)
Family emergency

If anyone can think of anything else, let me know. Nosey neighbour at the ready. Lighthearted please

Why would you move in on the same day unless you absolutely had to, because you were in a chain?

When I bought my house I was away on a work trip on the completion date and had my partner pick up the keys. I moved my stuff in a couple of days later, but DP lived round the corner in a nice comfy house with all her stuff in it, so we didn't bother unpacking, just went home to her house and lived there while we sorted out the new place.

We didn’t move in straight away, mostly because DS is autistic and it would have been living hell to do it in one day. Instead, we managed to paint and carpet his new room exactly the same as his old one and get a few more jobs done which made it so much easier when we finally came to move in.