Ok here goes I will use Humboldt face mostly when blocking down big straight spars ( main ). On laterals I would use a mixture of open face and 45 degree face and what the hell even a humboldt depending on the lean of the lateral, my position, the size of the piece and a bunch of other variables. Situation situation. I could never say I am only going to use open face when working in a tree. There are so many different cuts and we need to know when and where to use them. Just my $.02.