Actually, you may be surprised how good speakers can sound near, 1 - 1.5 feet, from side walls. Depends on many factors I pointed to in a previous post. My findings based on doing many hours of listening tests with speakers not necessarily sold for corner placement. Be careful with absolute type statements in audio. They rarely, if ever, turn out to be absolute and universal.
I can safely share this one absolute statement. You must try all the various placement and listening positions options available in your space. Pick the one that sounds best to you. It may mirror conventional wisdom, or not!