It's great having the option to create tasks in Shotgun not related to a project. There's also a permission setting allowing users seeing these tasks, perfect for us so far.
So we are experimenting with non-project tasks on a non-project-custom entity to achieve a project-comprehensive time logging. Sadly a time log on such tasks is still requiring a project to be linked to.
For all the required project link field in the time log entity, it would be great having the option to create time logs in case there's no project anyway. Maybe by making the project link field not mandatory by default, or at least as client having the option to override this by choice somehow.