Angular >2 Subject subscribe directly or use a method?

I have a service with a Subject member. The Subject provides an instance of a class:

public selectedProjectSubject: Subject<Project> = new Subject();

The value of the Subject is updated with a method:

public updateSelectedProject(project: Project) {
    this.selectedProjectSubject.next(project);
  }

In several classes i subscribe on the Subject:

this.projectSubscription = this.projectService.selectedProjectSubject.subscribe((project: Project) => {
      this.projectSelected = project;
    });

Is it a good practice to subscribe directly on the Subject or provide the Subject (Observable) with another method?