> The counterpoint to this is if you aren't specifically assigned tasks you're basically expected to go through the backlog to hunt for things to do. In most companies the backlog is never empty and so you don't really get any time for any of these ancillary tasks.

In my experience, most companies have some baseline level of work they expect you to do as an employee. Once you complete that, then you have some flexibility to choose the work that you do so long as it adds value to the company. It is also important that your work is perceived by your manager/peers to add value too.