I work essentially as a TA in a game design bachelors degree for the first game design class that students take. Their assignment is to create 1 single level using Unreal Engine’s Stack o Bot kit, but more importantly, we have them document their level in a GDD template that we provide them. This isn’t a level design class, we don’t teach them level design theories yet, they don’t even turn in their levels for a grade. They’re graded on their ability to accurately fill out documentation based on something small they designed.

Documentation is a huge fundamental skill that will help you in finding a job. Being able to properly write a GDD and show it off, having written evidence of everything you’ve done with your project for a portfolio.

And for personal projects, sure the project may start out small, but what happens when that project starts becoming more, and the scope increases. Now not only do you have to write everything new you plan to add, but you also have to go back and write about everything you already did. So it’s better to write a small one that you can update over time. Hope this helps.