"3 against 1" does not make sense to me. Usually it is ''3 against 4" or "3 against 2'' or "6 against 4". You see '1' beat does not make a measure, and as far as I know, these polyrhythms always put one measure of time signiture versus another measure of time signiture.
Maybe you mean 6 against 2?
Explain further please, so I understand?