The shutters weren't completely closed, so outside daylight may have made a difference earlier on.
the external blinds closed but with some slats open
https://www.mccannpjfiles.co.uk/PJ/GERRY-MCCANN-10MAY.htm
Despite everyone agreeing that the Payne's did no checking, Gerry said;
On Wednesday night, 2 May 2007, as well as he and his wife, he thinks that DP also went to his apartment to confirm that his children were well, not having reported to him any abnormal situation with the children.
Jez Wilkins knew the night before (Wednesday) what the group were doing;
Jeremy and Bridget became aware that although the McCanns had taken up the use of the creche facility during the day, they had not done so for the evening hours and had left the children in the apartment but were checking on them regularly and that other members of the group appeared to be doing the same.
They expressed surprise over this.....
https://www.mccannpjfiles.co.uk/PJ/JEREMY_BRIGET.htm
Thanks. I've only skim read GM's ws which states:
He is certain that, before leaving home the children's bedroom was totally dark.This aligns with KM's account where she states she could not even make out whether or not MM was in her bed without the light on. And yet GM had a proud parent moment thinking how beautiful MM looked. GM does not say he lit a candle or shone a torch or put the light on so how exactly did this proud parent moment come about if the room was
totally dark?Was he embellishing to convince everyone, including pj, his checks were as thorough as he claimed and to assuage any guilt he may have felt?
It seems to me this whole checking thing was not about whether any of the children would wander off, come to some harm in the apartment etc but simply to listen out for any crying. If this was the case why not just listen at the window/shutters? Did they even leave the shutters/windows partially open so they could simply walk around the front and poke their heads in?
Is this the reason JT saw GM and JW but they didn't see her? Ie if GM was checking via the front he would for some of the time be in a different location to the one he would be in if he was checking at the back.
The above is important imo. If GM did not observe MM at approx 9pm it would mean GM/KM last saw her at 8.30pm. Therefore she could have disappeared from any time between 8.30pm and 10.00pm meaning some alibis may not be so strong.