Kasha, in fact, many frum schools do not use R. Falks sefer, since he has so many chumras in there that people confuse with halacha. For example, he has an entire discussion in exruciating detail of what types and colors and thickness of socks are permitted, when according to Reb Moshe, socks are not required at all, as long as knee is covered. R. Falk discusses the degree of reflection of light off of various colors of socks.
I am still waiting for anybody to provide a clear source that tightness anywhere is a real halachic problem.
EDITED