Does my blog have to be in the nav for SEO purposes?

Hey there! Total newbie to SEO and I'm wondering if my blog has to be in the navigation bar to help with SEO. Is there any advantage at all to have it up there? On that same note, I have a services drop down menu for my video production site. I have about 30ish different services that I offer. I have a page for each service. Should they all be in that drop down menu or can I just put like my 5 top services and then an "Other Services" button in the dropdown that leads to a page linking to all the other pages? That seems long winded - but pretty much do all of my pages have to be in the nav or drop down to get best SEO results or does the fact that the pages exist suffice for SEO purposes?