In order to reduce short-term memory load, is it possible to use one superuser account in the Django admin for multiple projects?
The Projects have independent databases with totally different purposes, hence centralizing the database isn't an option
Django asks you to create different Superuser Accounts for every project in order to keep them isolated, if the projects aren't centralized.
In this case, as there's a need to create superuser for every project, you can manage the usernames and passwords for each of them in your notes somewhere.
As you're a beginner, and create multiple projects for practice, no doubt, you can choose one username - password pair, and use it to login each of those project-admins.
One more option can be to save your username - password to google, which will help you by logging into your account automatically.
In this case, you can create a centralized database for each of them, and connect each of those projects with the former, which allows you to use one superuser account for each of them