Issues are added on the fly during your L10 as you review your scorecard, rocks, customer/employee headlines, and ToDo's, and anything else that's important for the team to talk about. On average you'll have 5 to 10 new issues added each week. You'll probably have 3 to 5 leftover from the previous week.
One of the main reasons you are adding issues is to get your off-track numbers, off-track rocks, and unhappy employees back on-track. Sometimes it's just an update to keep all your people in the know.
Yes, there are issues that the leader can and should be solving on their own, with their own teams, instead of bringing it to the Leadership Team Level 10 Meeting. Ideally, you are pushing your issues to the lowest levels of the business. If you can do that, it will free your leadership team up to work "on" the business instead of "in" the business.