I am not sure I fully agree here as some speaker placement rules really do give optimal musical engagement. That’s less about personal taste, at least in that one parameter.
An optimal speaker placement will not necessarily optimize every single parameter to a maximum: bass, soundstage, dynamics, body in low midrange, cleanness of sound (avoidance of excitement of room distortion) etc. There will be trade-offs, even though the overall most optimal musical engagement may be achieved.
Rules or not, in practical terms the optimal speaker position will depend on many parameters, and to some extent also on individual taste.