I want to avoid retyping the same things over and over. Next-gen projects allow creating a default description but I don't see this option in the Classic projects.
In my internet search I found two solutions:
1. Use an app to get this feature.
2. Create a custom Description field, as described in this post:
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.