We just turned on time tracking, and are looking forward to breaking user stories into smaller subtasks and estimating those in terms of time... As I understand it, when you turn on time tracking you automatically tell JIRA Aglie that you want the burndown chart to work off of time and not story points? Does this mean EVERY story now has to have at least one subtask with a time estimate in order to show up in the burndown? Lastly, once time tracking is on do I need to turn it on somehow for individual boards as well?