I cannot open two projects at the same time.
If I try, firstly I need to use different workspace, as suggested in this link: https://www.talendforge.org/forum/viewtopic.php?id=15644 "Cannot open another project within same repository"
Then I was hit by user "email@example.com" already logon error.
Given that I can use "Folders/sub folders" to manage jobs, what are benefits to use multiple projects instead of one project?
Although, as you mentioned, I can switch from first project to second one, it's not possible to do the switch while a long running job in the first project isn't finished. You can work on the second job, while the first job is running if they belongs to the same project.
What are the advantages to have multiple projects? One thing I can think of is for the security reason you want to block some developers to read or modify the code developed by other developers.