trade day of the week (TDW)

I have only crammed in my article 11 traded weeks.
this means, what is there 11 Tuesdays, Wednesdays and all other days. except for a few holidays.
according to the law of mathematical statistics – representativeness of the sample starts from 30…
it means, that I will have to reject at least another 20 weeks, ie. almost half a year, before there is reason to draw conclusions about your strong and weak days…