Can you install too many monoflow tees?

When someone asked me whether they should install one monoflow tee on the return side of the hw rads in a One-Pipe HW Main System, or on both the supply and return side, I quickly reached for my memory and understanding of Holohan's "Classic Hydronics," among other books Dan has written. I proudly told him that the rads above the hw main generally needed just one monoflow tee on the return and any rads below the main (downfed) should require two monoflow tees. One on the supply and one on the return.

He quickly answered: "Would it hurt the system if I put two monoflow tees on every rad regardless of whether they are upfed or downfed, just to be safe?"

My knee-jerk reaction to this question was that it would probably not hurt the system, but it would be wasteful spending on his part.

Then I thought about it for a few seconds and said: "...you may be adding unnecessary restriction to the system as a whole on top of wasting money on something you don't need. Better stick to the one monoflow tee on each upfed return, unless you have a large rad, then maybe add the other tee. Now I am questioning that advice.

Your thoughts?