I have found that if you soak the wings in really hot water for an hour or so, you can pull the primaries section away from the other secondaries and coverts. Then I clip the two sections apart. This lets me salvage most of the feathers on the wings. The primaries are clipped with cutters or heavy duty scissors and the smaller feathers just pulled off in chunks. Just take your time and you get many useable feathers.

I think the hot soak softens the meaty parts enough to make them a bit pliable.

This is just my experience so do not consider it the 'proper' way to proceed.