why do search engines?

Question

I was looking for a search engine submitter for one of my sites and it said if I wanted to auto submit my site like every 3 months.

Answer 1

Resubmission is unnecessary. Once a site is in a search engine, it's in unless it gets banned for trickery. There is no reason to re-submitting a site to a search engine.

Answer 2

You can't spam it, the duplicate is automatically deleted if it's in the crawl list, but there's no use in resubmitting.