So you have "no clue" about one of the most elementary concepts in statistics? OK.
No... I said I don't know what that phrase meant....
Actually, there isn't. See above.
According to your "rule", since there are 2 possible outcomes to a coin flip, 2^2 = 4 coin flips is a large enough sample to tell whether the coin is "fair" (has equal probability to come up heads or tails).
But in four flips, a fair coin will give four heads OR four tails 12.5% of the time. So 2^2 = 4 flips is in no way a sufficient sample size and clearly your "rule" is nonsense. Whoever told you that "rule" was either simply making it up, or you misunderstood them.
I didn't say it was a rule.... I was saying that smaller sample sizes aren't quite large enough for a conclusive result.
(I have a PhD in experimental particle physics and teach a statistics course at a major university, by the way).
That's nice. It neatly explains why your analysis is so complex.