Submit your site to thousands of search engines. There simply are not thousands of search engines. People are confusing apples and oranges here. In this sense, not even Yahoo is a spider search engine. The problem is that what and how you submit to each of these sites should be done in a different way.
FFA submissions are generally very low impact types of promotion.
Especially when you are submitting to the same list of FFAs that everyone else is. Meta Tags will get you a high rank. That is just patently false. Some engines don't even recognize meta-tags at all. The mathematical formula, or algorithm, used by the engines is generally fairly complex.