The simple short answer as to how often you submit your website to a search engine is "You only need to submit your website to the major search engines ONCE!

Submitting your website many times has no effect on your position in the search engines. It will not affect how quickly the search engine crawler gets around to actually spidering your website either and it will also not affect the frequency with which the search engines will re-visit your website.

If you think you have been missed by the search engine crawler, don't panic, it can take as long 6 weeks to get around to crawling (spidering) your website. Don't be tempted to re-submit your website as it may have a penalty attached to it for spamming.

Remember, you only submit your website the ONE time

Which Search Engines Should I Submit My Website To?

First of all, what are the major Search Engines? The top 5 search engines often account for more than 95% of all Internet traffic your website may receive from the search engines. Below is a list of the major search engines.

Major Search Engines To Submit To (only Once remember)-

1. Google - Often called the biggest search engine on the Internet, it is also the most popular according to some recent polls. This search engine is entirely free for the primary listings, and offers paid listings at the top of the search results, as well as their AdWords program which shows small text banners on the right hand side of the search results. Google bases its search results on website content as well as their patented PageRank algorithm which factors in links from other websites to determining your rank in the search results. Submit to this website at http://www.google.com/addurl.html and your website should be in the index within a month, sometimes two.
2. Yahoo! - Second most popular, and probably the most famous of all search engines, this icon among web portals controls the search results on MSN.com, AltaVista.com, and Alltheweb.com in addition to its own search results. Submission is free, and I wouldn't recommend paying for inclusion in this directory at this time, though paying to be in the directory is a good idea if you can afford the $300/year. To submit your website to the search engine go here: http://submit.search.yahoo.com/free/request
3. MSN - The third most popular search engine, MSN, uses Bing for its search results.
4. AOL - This popular search engine uses Google search results as its primary and paid listings. See Google.
5. AllTheWeb  - Purchased by Yahoo!, this once promising search engine now uses Yahoo! results and will probably be used as a side project by Yahoo! for various purposes.
6. AltaVista - One of the oldest search engines on the Internet, AltaVista was showing its age until Yahoo! purchased it in 2004. It now uses Yahoo! results and is basically just another portal for Yahoo!.
7. AskJeeves / Teoma - The Teoma index powers both the popular Ask.com website and its sister site Teoma.com. You can only get into this index through being found by the Teoma Crawler, or via paid Inclusion which you can order through http://www.positiontech.com/askjeeves/index.htm

The above are the main search engines on the web which you can submit your website to, if you know a website that is not on the above list, chances are it is using search results from one of the above search engines or indexes. There are some search engines that utilise the major search engines listed above, Dogpile is one example. http://www.dogpile.com