We have done team fence signs for multiple schools for years. Working on an order for a softball team this week.
If the banner is tight it won't whip, thus tearing it. Too much tension on the corners and grommets tear out, even though the max shear is in the center and works it's way out to the edges and then to the corners. Yet we expect grommets in the corner to resist the wind of the whole banner. We mostly use 75lbs zips, but we space them accordingly: a least every 12" for a 'free air' install, 24" on walls. Standard ball field fence banners are every 12". We've been doing 4, 4'x64' mesh banners about 32' feet high on top of the high school football bleachers for a few years now. The two facing the field are on chain-link and the two facing the parking lot are on an aluminum tube frame.They have grommets every 12" and extra webbing in the corners. We only use black zips since they are UV resistant and double them up where needed. We stretch them tight.
Hope this helps