Placement of rear speakers I think is really important. Not so much in the back of the room but on the sides so the sound is received directly to the side of your head.
But I find that without rear speakers you still get sound from behind you from the reflections which Is fine, and sometimes preferable. But even with that I’m not a big fan of rear speakers because the quality the recordings is seldom that good to take advantage of it.
Sure occasionally you get targeted rear channel effects but it’s kind of annoying most of the time.
subwoofers and main speakers that’s all you need.

