I am finishing my basement. Walls and ceiling will be covered entirely. I need to install junction boxes behind the ceiling (up in the joists) or inside of the wall itself. From what I understand, the main consideration for this is that the junction boxes need to be accessible after the area is finished. For this I plan on using a wall panel to open/close access to this area.
What I have not been able to find information on, however, is how many you can put in proximity to each other. I have provided a picture here of a tentative install (they are nailed in place, but easily removable) of six junction boxes in an area between two wall studs. I will not be insulating this stud bay. I will fireblock the above area and ensure to my best ability that it is air tight with expanding foam and fireblock.