I understand the philosophy here completely. What I don't personally know is how the NHL sets up their departments. I can speak to the NFL.
Generally, A prospects are those given a Grade of Round 1-3. At least five people do indpendent evaluations -- the local area Scout (Southeast, etc), the regional Scout (East), a national Scout, the head of College Scouting, and then the AGM or whoever is ultimately in charge of the amateur wing. That's 4 independent instances of cross-checking designed to filter out outliers.
Then of course it's up to the decision makers to synthesize the info well.