The objective of any issue is to close it. To that end the life of a ticket flows like this for us:
* anyone can create the ticket, the ticket is 'open', but unassigned.
* someone decides to start work on it, so changes the ticket to 'in progress' and assigns themselves to it
* they fix the issue and close it.
Sometimes a ticket is open because what needs to be done is unclear, during that time the ticket usually stays unassigned as we discuss the topic for clarification on how to proceed.
'Open' issues are the ones that are in need of most immediate attention, then for stuff that is to be done, but not so important, it goes in the 'Back Burner'.
Most of the time we use the "Private Tracker" option set to checked so only our team can see the issue. This gives us the ability to discuss how to proceed without additional input.
When a tracker is marked as not private, others can see and comment on the issue.