In Agile, you are supposed to ship product on a regular cadence. All features are added to a product backlog, divided into small projects that fit within a sprint, and then prioritized. The backlog is just a way to keep track of all of the ideas people have, requests from customers, major bugs and other things.
The first patent for Pristiq is set to expire in February 2022. This is the earliest predictable date that a generic version of the drug could become available. However, other circumstances could come up to extend or shorten the exclusivity period.
If a patent is granted, it will expire 20 years from the filing date of the patent application. If the patent office takes longer than three years to examine and grant a patent, the term of the patent may be adjusted accordingly. In some ways it may be beneficial to the inventor to have a long wait since the life of his patent will be extended.