Clarification for Phalaenopsis Shade Requirements

[HiOrcDen]

I have read various things online about the light requirements for Phalaenopsis. One place I read they need as much as 75-80% shade. I read elsewhere that they thrive in 3 or 4 hours at 60%, and therefore 70% is suitable all day. I also seem to recall a difference between requirements for Novelty species and perhaps other species. I'd like to get some clarification

Oh and one more thing. Suppose I keep my Phals the whole day in 60%, and that would be too much. Could I add, just for them (and other low light Orchids), a simple window screen, something along those lines, or anything specified to shade about 10% more?