People on the board have suggested using ping pong balls, on a still day, to help adjust the returns. Boy, I wish I had known about that when we first "inherited" our pool.
I have one skimmer located on side wall closer to the deep end, end wall. Until last year for above mentioned reasons of movement of floating debris I had the three returns, on each of the shallow end walls pointing upwards just a bit, so there was just a slight disturbance on surface, and all three pointed in direction to circulate the shallow end water towards the skimmer way down by deep end. There is another return across the pool from the skimmer. I found that aiming this return directly at the skimmer, pointed up just enough to cause a slight ripple on surface, pulled the debris that went past the skimmer from staying stagnant at the deep end and shot it across the pool to the skimmer. So what could have been, on the surface, a dead spot kept the circulation going towards skimmer.
I put in two PoolSkims on the two side walls in shallow end. They have a lot of flow. To get enough flow to the PoolSkims I had to restrict the flow, using eyeballs with tiny holes, on the two remaining returns. I installed the PoolSkims so that each continued to circulate the water as before but even more powerfully than the previous returns. The shallow end wall, with restricted flow is now pointed downwards and directly towards the deep end. I didn't want to restrict the return that is directly across skimmer but had to to get adequate flow to PoolSkims but it has just enough flow to assist moving water from the potential "dead spot". It just takes a little longer to move it.
"Favored, most trusted pool guy" was here, yesterday installing my new filter and pump.

I asked him about the eyeballs that have a slit in them as I wanted to experiment with gently pushing water down the wall, in shallow end, in a fan flow, to help move some sand/silt a little away from the curve from bottom to wall. He didn't think it was a good idea (consensus from some of our TFP experts). He also suggested that when I took one or both PoolSkims out of the pool for summer and put the "normal" eyeballs (1/2" hole) back on the flow coming from the "slit" eyeball, pushing that much water down the wall, could potentially damage my 14 year old plaster that I abused for years (scaling from high pH and three acid washes) before finding TFP.
BTW.... It took me a whole summer, when we first moved in, to get the returns exactly like I wanted them. I had to do "compromise" adjustment so I could keep them in the same positions during all seasons, when prevailing winds change directions.
Now that all my return eyeball fittings are new they are much easier to adjust.
gg=alice