Overflow placement - 1 vs 2 returns?

[Aquattro]

My return simply returns water from the sump. I only have (maybe) 400gph, so regardless of how many lines I use, it's not adding to flow in any amount worth worrying about. The only time I used dual returns was on a 150g running a MAG 18, and even then the flow was minimal.
IMO, use the return pipe how it best fits and address flow using pumps designed for that.