I have been thinking a lot about site learnability lately. I remember being told that 7 items in a navigation is the most learnable for visitors. I think this has to do with human memory, and the scan-heavy nature of the web, but I am not sure.
Along with the above, I have been told important navigation items should be placed at the beginning and end of the navigation. The idea behind it being users will skim your navigation when they visit your site and only remember the first items and last items.
Are there any resources to back these ideas up, or are these just industry standard/ best practices?