Every pool is different. You should perform your own experiments with your returns.
Some pools have their returns located all around the pool and can move all of the water in a circular motion. Our old pool had only two returns, but they could move that water all around a 16 x 40 foot pool. Other pools have their returns on one end pointing towards the skimmers on the opposite end; the water flows across the pool.
It is not necessary to have the returns pointed up in order to have the water, including the surface water, move in a desired direction. We keep our returns pointed flat out. The water surface doesn't get broken. One can watch as leaves fall into the pool: they travel all around the pool and then float into either of the two skimmers.
Some people like having their returns pointed up to give a little bit of action to the water as a personal preference. I like that ours are flat out because it is easy to see every tiny spec of dirt either when vacuuming or when suffering from an attack of Chronic Sparklypoolitis, especially right after putting the vacuum away.
We turn on a water feature when we need the pool to "look sparkly".
Lana