YANBU, rental inspections are intrusive and demeaning. I can understand one after several months (to make sure you are living there/not subletting etc,) and are looking after the place, but when you have been there a year or more, I see no need whatsoever for inspections more than once a year just to touch base, and see that everything is OK.
Some years ago (late noughties,) we were renting privately, (for several years,) and we had a couple of quick inspections over 1.5 years, that took 20 minutes each - the letting agent looked around briefly, chatted for a bit, was very happy, and then tootled off. Fine.
Then someone else took over the letting agency, and he was a real twat. He got a different inspection agency altogether (not someone from his office who could take a quick gander and say 'things are ok.')
They said the inspections would now be 3-monthly, and during the first one, they stayed at least an hour and a half, and on the second inspection, that was only 10 weeks later, the man who came insisted on taking photos (to send back to the landlord.)
It felt a bit intrusive, but the tenancy was up for renewal, and I didn't want to risk the tenancy not being renewed because we were 'awkward.' So I agreed. The man who came took approximately a HUNDRED photos. I was gobsmacked and didn't know what to say or do. He just kept snapping them off (DH was at work, I wish he had been there.)
We had around 10-11 rooms and he took around 10 to 12 photos in each one. Including our bedroom (and our kids bedrooms.) I found it so intrusive and awkward, and when he went, I got very upset, and wished I had stopped him. I thought 'these people have over 100 photos of inside our home now and all our personal effects.' It was so weird and I am sure it was not normal.
Thank F that 3 months later (just before the next inspection was due,) we moved out of private let, and never went back! Horrible experience.
And yeah, the 'all-day' time frame is ridiculous.
And if I were you, I would refuse to let them take photos. It's unnecessary, and weird. To me, it was like a kind of 'we own this house, we are in control, and we will do what we like' kind of attitude.....