I've always read it that way.
The 'checking system' always sounded like bollocks to me. Are a group of 7 or 8 friends really going to have someone getting up every 5 minutes? And if yes, why? If you feel the need to check on the kids that much, isn't that an obvious indicator that they shouldn't be left alone? I don't think the checks were as regular as we're told.
As for Tannerman, I'm not sure of the timeline and when he came into existence. However, I've always wondered if the sighting was embellished upon, or even fabricated, in order to steer the investigators towards an abductor. There's a certain logic to it.
Basically, I think they told a few fibs in the beginning in a bid to dodge any negligence charges, and it panned out worse than they could've imagined. The internet picked up on the descrepencies and ran with them. It didn't help their case that they've played the worst PR game imagineable. The McCanns have always come across as very difficult to like - especially Gerry.
That is my theory was well.
It was clear from the disparities between the PJ interviews and the Leicester interviews that none of it made sense. It's a good example of why witnesses should never hot house their version together.
My guess is she really saw Totman, and enhanced it for whatever reason. She might have questioned her own memory over where she saw him or forgotten. Maybe the Pyjamas is the only thing she really remembered. I think Murat gave her the opportunity to exit her story and she simply banked on PJ having the right guy.
The problem is, all of it created a false timeline and cast suspicion on the group.
But what we have to get in mind is the Met had years to speak to all of them in private and I suspect they got to the bottom of it. PJ had no access to any of them.
It is one of the biggest problems of the case that so many witnesses were on holiday and left the country.