20 are maximum. Just because of that simple arithmetic, you understand that they lie to you. They play on probability. It is the same as playing lottery, Black Jack or roulette. You can win in a short time, but more often you loose in a long run.
Web promotion is the same kind of gambling.
You must know that only few search engines and directories utilize meta search technology. More than that, they change their search criteria very often, and that criterion is kept in a big secret. Shortly, this criteria has been changed again. They have hidden keyword text and meta tags that fool the search engine. Those are they.