Despite what many people will tell you, you could never update your site and still get and maintain great rankings.
It depends on your site topic. Is it something where there is a reason to constantly post new content or are you just doing it because you heard that was a good thing for SEO?
If I built a site about how to get rid of pests and different bugs, once the site content is complete and I have covered the major pests and insects, there would be little reason to update the site very often, and surely no need to post daily or even multiple times a week. It would still be a great site and cover its topic in total detail.
I would also make the argument that adding new posts regularly can actually hurt your rankings rather than help them, especially if you have a dynamic home page. Every time you make a new post, you are screwing up your site structure, internal linking, and probably weakening the whole site.
Big authority websites can get away with dynamic home pages because they have an ungodly amount of excellent links coming in to them. Good links will overcome 95% of SEO defects on a website. Nobody here has that kind of website.
If you visit a lot of internet marketing forums, just think about it. How often do you see people start new threads saying they add new posts to their site daily and their site is still not ranking OR the rankings are constantly bouncing around all over the place? Often times, it is BECAUSE they post so often that their rankings are not stable.