>> However I think a lot of developers (Particularly startup ones) have multiple roles, so interruptions and changing flow is a part of the job.

That's how my last job was. Tasks varied as followed:

* Work on upcoming project X (release date in the future)

* Feature request on project Y (need done somewhat soon for a client on an already operating project)

* Bugfix needs done NOW on existing project Z

* Ops issue with servers, database, etc