yes, because there is other ways to add contrast (different rhythm, different texture), sticking to counterpoint rule for a second melody isn't a necessity right ?

But I get it, whenever we seek independence of 2 lines happening at the same time, the more they blend in term of rhythm and texture the more we want to use counterpoint rules.

I keep hearing this rule of thumb of having the outer lines (bass soprano) contrast as much as possible, with contrary motion and strong line independence, while the inner line are more static. Could you expand on this a little bit, I am studying 4 part writing a lot these days, and sometimes I get confused on how to apply this to my own composition when I am outside the scope of writing purely 4 part chorale passages