I hit tris with chest and bis with back on mon and tue, then arms again by themselves on friday.
I like hitting tris/chest and back/bis simply because they are already fatigued then I will hit some reps with light weight and really focus on contrations. Then friday when I do them by themselves I alternate bi/tri, bi/tri and really go heavy.
Try it out, it may work for you. Working my tris secondarily with chest on mon, by themselves on tues, then secondarily with shoulders (heavy DB presses) for me I think is too much. Then legs on thur and arms again on fri. But thats just me. It may work for you and the only way you will truly know is if you try it.