Why would you have backtracking? Either go to the end and turn round
Errrrr......entering the runway taxiing down it and turning around at the end sounds awfully like backtracking to me.....and while you are doing it you are stopping anyone else from using the runway so it stuffs up the movement rate.
or have the taxi-ways and the runways form a triangle.
That's possible I guess if you have the land available and don't want to build terminals etc on the green space you've bought (TBF many airports back in the day were triangular in form, but it was often a triangle of three runways, often also with parallel taxiways).