There's no right and wrong answer. I'd say post as often as you can provide value and useful information. Don't just pump out articles to gain more indexed pages. Sooner or later you'll get tanked for this kind of strategy. Your overall site quality goes down etc..

You can post all at the sam day

It would be better to prepare yourself a long-term strategy or plan and stick with it. For example, add one fresh original article to your website everyday and do this for a long time because trends do play roles these days. Usually the more original contents on websites, the better and the more fresh materials are added to them, still the better. Try to write compelling copies that will make a big impression on the audience, win their praise and help win links. Such contents will gradually help gain finer positions on search engines too.

Ideally, it’s best to post a new content every day but that’s not possible. You should come up with a schedule as to when you’re posting new content so that your readers would have a better idea of when to check back your site. This way, you’ll be able to keep your audience and your sanity as well.

In case you run out of content, seek help from professional writers and when you post, make sure that they’re all relevant or else you’ll lose more and more readers every day. Keep the new posts coming!

Good luck.