IMO the first interview was rife for misunderstandings. Gerry had had no sleep and was still in massive shock. Any idea that he was cool calm and collected is absurd IMO. There would be delays because of the necessity for translations -- and IIRC his replies were then typed out by the Police officer at the time. AT that early point and in those circumstances then IMO Gerry would find concentration very difficult and he would still be hoping and praying that news that Madeleine had been found would come at any minute.
There is no credible reason that I can think of why anyone would lie about which doors they used. What would they have to gain by doing that?
On the other hand we know for definite that different people had different opinions on which door constituted the front door and which door they regarded as the back door. It seem obvious to me that until they sorted that out then major confusion was inevitable during interviews.
IMO that was sorted out at Gerry's second interview.
First statement by Gerry is that he used a key. Then he asserted that Kate used a key. The guests were given but one key per couple, so said key had to pass from Gerry to Kate, somehow. Unless, of course, Kate did not use a key, or Gerry did not use a key or neither used a key. Confused?
First statement by Gerry also says Matthew went via the open patio doors. It seems the McCanns avoided the short route of the open patio doors and went the long route and used a key.
In Gerry's second statement he confirmed that his first statement was accurate. Then he changed the account to everyone going in through open patio doors, no key required.
I believe he did a video about a year after the incident, in which he returned to 5A. And in which the key was on a table in the apartment and the reason for using the patio doors had become 'the noise of the front door might wake the children'. Not so the other 2 couples on the ground floor.
I am neither pro-McCann or anti-McCann, but Gerry's first statement has hallmarks of someone trying to cover over a pile of poo, and doing a very bad job of it.
There is a credible reason why this might have arisen. It has nothing to do with fatigue, stress or disorientation. And no, I do NOT know this credible reason is what actually was the driver.