Management consultant here; this is literally what I do probably 50% of the time. Our buyer has a strategy they want to implement, so they hire us to help them sell it to their boss. Usually we improve them of course; but our buyers can generally handle this stuff on their own -- their bosses don't trust them, and want someone else on the hook.

Trusting subordinates who are incentivized to fudge the numbers is very difficult. Most people won't outright lie to their boss to get ahead, but they will make a bad business proposition look good to the point they genuinely believe it themselves. Leadership is hard.