https://news.sky.com/story/serotine-bats-use-penises-in-bizarre-way-during-sex-scientists-say-13012547
Some have more inches than appears is of use.
Oh ok.sorry thought this was about something other than a box.
I think the size depends on the room size if you have a small room sticking a huge screen in there can look rather out of place, equally a large room you don't want a tiny screen.