Sometime I use send 1 as monitor output.
(Out 1-2 is guitar and 3-4 is vocals)
All other outputs are then occupied for PA system.
I would like to insert 2 FX-loop-blocks to SEND 1 at different positions.
Now you can only chooze SEND 1 as destination for one FX-loop block.
Then you could actually send both the guitar-row and the vocal-row to the same monitorsystem without sacrifying any stereo signal (out 1-2 and 3-4)