just wondering why nick uses multiple media queries and guil uses just 2 media queries which are in 769px and 1024px

From my personal experience, I would say that the use of media queries vary alot from project to project. If the page layout works well on all devices media queries are unnecessary. Try out your sites on all kinds of devices, both landscape and portrait mode, and see what media query rules that best suits your project.

Tl:dr, sometimes orientation isn't necessary for your layout ?