One posting per week is too long. Your followers might forget about you but if you make a content like @sweetsssj with solid 13k plus followers then I think it's fine to do so. But for accounts, like we have I think we need to make more than one post per week.

I might be confident to do one post per week if I have thousands of solid followers, but for now, that we are still trying to build our reputation and organic followers, we need to post frequently as we possibly could.