Should I create 1 major project for my Product line with multiple epics, or multiple projects?

[AAAA]

I have a product line that is constant (i.e. iWatch) but continuously gets upgraded with new features or enhancements. Is it better to create one major project for the product line and create various epics assigned to different teams, or create various projects that have their own epics and stories?  

We've been using an old version of Jira that has 40+ projects in it for the Product line I mentioned above!  We are in the process of migrating these into the latest cloud version of Jira.  So, should we continue with the same setup and have 40+ projects, or should we create one project for our main product line?  

[Stephen Sayler]

I would think a single project makes more sense for a single product - it certainly makes things easier for organization.

That said, since you're starting from many projects, you could create backlogs that pull in issues from multiple projects, and see if that works for you before investing the time in restructuring the projects.

My one team operates in multiple projects simultaneously, and it works fine for Scrum purposes including

1. a single KanBan board for the current sprint
2. a single backlog from which we use quick filters for refinement
3. a holistic view in Advanced Roadmaps.

The biggest challenges we face are:

1. long lists of epics and versions in the side pane of the backlog - to mitigate this we prefix them with project abbreviations, and sort alphabetically
2. accidentally creating an issue in the wrong project - which is easy to fix by moving the issue in Jira.