This is a very interesting topic to me because I'm doing my best in trying to understand how Bitcoin mining really works.

I've never thought of the possibility of assigning different tasks to different miners and I'm not sure about if that even possible, taking into account that S9, for example, does 14 tera hashes per second, but here's what I think. What if it would be more efficient to make each miner to try to find nonces for different sets of transactions rather than finding nonces for the same set?