It is, indeed, quite remarkable that no one ever bled any apartment other than in apartment 5a ...
Or is it that Eddie (finally) detected a scent of blood in apartment 5a because the dog spent far longer in that apartment than any of the others.
Or could Eddie's, apparent, "reaction", same as (undoubtedly) cuddle-cat have been alerting error?
Yep, quite remarkable as you say. >@@(*&) Similarily quite remarkable as Kates finger prints being the only ones found on the window >@@(*&) yet everyone would be fiddling with it looking out.
Also remarkable that the Front door was totally and utterly ignored as a possible entry point.
Yet it was the most likely place, as it was deeply recessed in a very dark spot, and completely hidden to anyone crossing the front parking lot to block 5.
Also strange that the PJ told Gerry that they had proof that a dead Madeleine had been carried in their hire car. A car that wasn't hired until several weeks afterwards.
Of course an empty threat, a lie like that

, was preferable to torturing Gerry ... to illicitly get a confession out of him ... very sinister tho !