Zhang zhuang is practiced in lin kong jin or empty force. Here`s a link: www.emptyforce.com
As for me, I practice standing, but not for long periods of time. I usually do it for about 15 minutes. I use just normal standing, holding the ball or sometimes I stand in positions from my katas.
I mostly learned about standing from books by Mantak Chia, B.K. Frantzis and I`m begining to read The way of energy by Lam Kam Chuen. I try to add these teachings to katas.