To be serious though, we dont go smaller than 1/2". Between my guys mis-sizing and stocking the trucks, and future expansion ability we opted years ago to use at least 3/4 and I cant say I mind it.
1/2" is just sort of chincy to me now.
Inventory and ordering pipe and everything is easier.
Once I looked at the hard savings on materials, the labor costs of jacking with the extra pipe size seemed to about even things out.