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My rule of thumb is, once I'm in the database, I submit only when I make a change. Once I have a good position, I don't submit again unless (until) that position falls -- I don't mess with success. I watch my logs for the spiders and if they spider me, I wait to see the results before I submit again. Others have their own techniques, and there's more than one road to success.
Used to be Inktomi really benefitted from frequent submission. Right now, it seems like pay them or forget about it.
To answer your direct question, once a month should be fine in terms of not hitting any spam penalty. Outside that, it's good to research the Help pages of each major search engine for statements. They change their procedures all the time and you easily learn something before anyone else on the forum.
Serg, it feels like you may be from a technical background and would like straightforward "A follows B" answers. Unfortunately, there is as much art as there is science in search engine positioning (and maybe even a little voodoo as well). I wish my answers could be more precise -- but that's the nature of the field.
Don't believe anyone who tells you they have the easy road to search engine rankings -- they only want your money! It takes sweat and marketing savvy to build traffic to a site.