In Pa it's 250 square inches of blaze orange on the head, chest, and back combined during small game, deer, bear seasons. Some overlaps exist with early muzzle loader and archery where the orange requirement is in effect. For groundhog hunting, only an orange hat is required. I think fall turkey also requires orange, bit I don't hunt fall birds due to small game and archery hunters being about, which is too crowded for me, so I'm not sure. For doves, waterfowl, and late flintlock, no orange is required. I have seen people get cited for not wearing blaze orange. Saw a guy during pheasant season get a ticket because the hat he had on, although a shade of dirty dull orange, was clearly not blaze orange.
I wear orange when required to do so, and do not when not required to. If I had my way, I'd never wear it, as I do not think it helps to prevent accidents much.