I think this "would" in "whenever his subordinates would make a proposal" means not "willingness in the past" but "a habitual action in the past". Even in the subordinate clause,"would" can make such a meaning. But is this common?
st224)Not long ago I did a series of creative thinking workshops for the executive staff of a large computer company. The president had called me in because he was concerned about the stagnant thinking environment at the top. It seemed that whenever his subordinates would make a proposal, that's all they'd make ─ just one. They wouldn't offer any other ideas. Since they had been trained to look for the right answer, they usually didn't go beyond the first one they found. The president knew that it was easier to make good decisions if he had a variety of ideas from which to choose. He was also concerned with how conservative this "one-idea" tendency had made his people's thinking. If a person were presenting only one idea, he would generally propose the "sure things" rather than take a chance on a less likely off-beat idea.