We've slammed over 120 poles in the ground for paintball purposes, and another 80 for a golf driving range, NONE of which have shifted or tilted since installation. All our poles are 7-8 feet in the ground, corner poles or any with a shift in the lateral force (corners, etc) are 9+ feet in the ground. It's important to pack them with 3/4" down limestone or something very coarse. Do NOT use pea gravel or anything rounded, as it just settles upwards as the pole vibrates, and the small crushed limestone does the same. Also, spacing is important: we went every 10' on 20' netting, but we have high winds and I refuse to do all the setup and repair everytime it blows a bit. We have NEVER had any issues with paintball netting. Ever. Once it's up in Spring, it stays up until Halloween with NO maintenance, but we did it right the first time!