The animals can choose between 8 nest boxes with test flight holes of various sizes, from where regular 4 - 5 are inhabited. The Habau 2975 nesting boxes are indeed regularly inspected by blue tits, but related more other boxes. I suspect that it is because of the size, since the other nesting boxes offered are significantly larger.
At the positioning it is not according mM. After cleaning in the spring of the boxes are "somehow" hung up again that there is no any case again to the same place.
For example, I have changed this year when hanging the place of Habau with one of the other boxes, which was occupied twice with Blaumeisen last year. Result: The blue tits are moved.
Each of the other 6 nesting boxes was occupied at least once, most have been frequently related.
The great tits and sparrows also among my "house guests", punish the Habau - boxes with contempt, although one of the entry holes is set to "tit size".