I place my gear where I can... due to very limited space for the studio.
I do try to observe as many of the rules for placement as possible.
Tower on the floor below the desk.
Monitors on desk about 6 feet apart. One is on a makeshift shelf, the other in in a boxed in bookshelf ares (pictures are on my website)
Sub on the floor to my right firing into the room.
I must work within the limitations of the system and the environment.