KingYen depends on the school but generally i think if your scores average out to an above/top 20 (bare minimum) you have a good chance of getting into nhs/schs (in later rounds). what i mean by that is like if you get a superior and a below average together the average of them is prolly an average/above avg. so lets say:
top 10: 3 points
top 20: 2 points
above avg: 1 point
avg: 0 points
below avg: -1 point
in the case of the guy who got 2 sups, 2 aa and one ba the mean of those is 3+3+1+1-1/5 = 7/5 = 1.4 which puts him in the above avg to top 20 category. if someone got 3 sups and 2 bas it would be 3+3+3-1-1/5 = 7/5 which is again above avg to top 20 territory. sorry for the yap but to answer your question, i'd say it takes around 2 sups to cancel out a below average. and pls dont listen to this i just made up this score cuz it was fun lol