Assuming if company ABC settle short interest dated on September 8 (does it have to be mid or end of each month for every company to settle short interests or it is only when they have to report?), FINRA will issue record date at Sept 15th? If short ratio is 10 days and SI record date is Sept 15th, does it mean the shorts will need to start covering on Sept 25th?
The short ratio is the number of shares sold short divided by the historical average trading volume. Source
Shorts are generally not required to cover their positions based on a fixed number of days. Instead, it depends on borrow availability and margin requirements. A short position can theoretically be open for years.