Those are decisions every owner makes every season. There are no hard and fast rules. Some owners swear by 20 med so that they can pump up injured players -- others consider it a waste and go with 0. Most, as you'd expect, go between. Scouting impacts both the number of players seen as well as accuracy of ratings, but 20 doesn't guarantee accuracy and still won't reveal every player that someone else may see, even some with lower budgets. Experience and your particular approach will dictate, and you may find you use different budgets depending on your team's position in a given season (rebuilding, competing, etc.).