Do you have projects setup that are timeless? for instance, projects that holds tasks for clients, custom templates, productivity boards, etc.
More importantly, do you love being able to see key Milestones from a Timeline view within a Portfolio?
Fear no more … simply make sure the Milestones have a due date. Originally, I was under the impression that you had to set a project date range for an extended period of time in order for the Milestones to be plotted. This isn’t the case! In fact, it is recommended you don’t do this as Milestones are easier to detect without an extended overlay of the project within the view.
Disclaimer: No need to set a Project date range if you want to be able to view the Timeline at the Project level either.
Thanks for pointing this out, @Bastien_Siebman. I ran across an explicit need to see activity from a Timeline view within a Portfolio and got ahead of myself by falsely stating a date range was required for a Project Timeline to work. I knew better; yet, got my information crossed when scoping this post. Good catch! I have revised the original post accordingly.
@Bastien_Siebman the only advantage, which I believe to be a rare use case, would be to see all milestones plotted across a portfolio of projects. You can achieve the same from an Advanced Report and view by calendar, but some users might prefer to see this information in a chronological view. Being able to scroll vertically across projects and see key achievements across multiple projects could be a nice way to evaluate big wins.
Funny though, a client asked me to code them a style fix to hide the milestones from that view I have the CSS code available to use in Stylebot Chrome extension if you want.
being able to see key Milestones from a Timeline view within a Portfolio?
Fear no more 
… simply make sure the Milestones have a due date. Originally, I was under the impression that you had to set a project date range for an extended period of time in order for the Milestones to be plotted. This isn’t the case! In fact, it is recommended you don’t do this as Milestones are easier to detect without an extended overlay of the project within the view.
?
I knew better; yet, got my information crossed when scoping this post. Good catch! I have revised the original post accordingly.
I have the CSS code available to use in Stylebot Chrome extension if you want.