Generally they fix the hernia. They don't want it getting any worse, as the hernia repair/intact diaphram keeps the wrap from slipping. From what I've learned, wraps don't fail unless the hernia repair fails (assuming they were done correctly).
Nissen Fundoplication 2/09
"Whatever you fight, you strengthen, and what you resist, persists.”
“Worry pretends to be necessary but serves no useful purpose”
“Accept - then act. Whatever the present moment contains, accept it as if you had chosen it. Always work with it, not against it.”