I have seen that diagram before but never tried it.
Anecdotally I’ve tried it and there’s no merit. The male seeds were female.. the female seeds were male.. I just toss whichever ones look healthiest and most mature in and hope for the best
There is a short article about how the environment, mostly temperatures, in the grow area can affect 1 and 2 week old seedlings and cause them to mature as females.
Do you have a link to the article, or will a google search yield it easily?