if i send a workspace project by PDF (or CSV) without schedule (just immediate sending), it will produce an entry in the list of "scheduled reports". this way, the more projects you send by email, the longer get's the list. an moreover, you can not filter which "scheduled reports" are really schedules or not ...
even i think this is a bug in implementation, i raise an idea to improve the "scheduled reports" list and ask for an additional filter:
- "active" schedules: would show only scheduled reports which are still active, will be sent in future
- "scheduled": will show all scheduled reports which have a real scheduling option
- "expired": will show scheduled reports where the expiry date is in the past
feel free to add more filter ideas in the comments