Speakers room positioning - diff tricks ?

Dear All, with Tube traps analyst suggestion, my speakers ended up positioned with 1/3 on their back with the listening position 1/3 from the back wall.

Wondering when this is the best trick to position speakers or shouldn't be just one of the many. For example I recently read the Cardas white papers and it seems to me that the speakers will ended up about 1/4 from their back wall and the couch 1/2 in the room, much different from Tube traps advises.

To wrap-up which one of the following is the most used ?
1- Tube traps room study
2- The speaker manufacturer manual advise
3- Just your ears ?

Tks for commenting. Soon my Avalon will arrive !