What "checks" do people do on a second viewing?

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A couple viewing our house are going to come back for a second viewing. They have already checked the walls for levels of moisture, checked gutters and had a good look round. They said the second visit will be very thorough as they have lots of checks to do and it could take 1.5 hours.
I know they want to look in the loft. Any ideas what else they will want to do?

Measure up for furniture etc?

check water pressure
check all fitted furniture
look at quality of windows

they might have a builder with them to discuss loft extension/conservatory...

Based on my experience of our first house then checking that all the doors fit/close would be a good start! Based on our new house, it takes ages to find all the quirks/issues/snags with a house. But, for example, windows/doors/security, plug sockets/fuse board (are there enough/what condition is that in), floors, bathrooms (signs of leaks/mould/what’s the sealant like), what is the water pressure like, and the hot water/heating system. They might be deciding between a full structural survey and a homebuyers report. It depends a little on the age of the house, and what work has/hasn’t been done to it

We remeasured all the rooms as the dimensions on the estate agents info didn't add up.

We would check where furniture could fit, maybe measure for curtains if new ones needed in bedrooms and look very closely for signs of problems that may come up on a survey e.g any cracks which look structural, issues with roof etc, fireplaces taken out without support as well as state of bathroom, kitchen. If its a house where work needs to be done trying to estimate extent of it and costs.

Never taken anything like 1.5 hours though. Having said that its most important investment you will make so its probably sensible.

I took my dad who is a gas engineer and plumber to discuss the potential to convert the garage/utility room and maybe in the future expend the kitchen.

If looking in loft maybe considering loft conversion or checking for signs of leak from roof.