Reviews take as long as they take. It’s not always as simple as getting more people on the review team as sometimes delays are due to them needing to consult with legal or other such things that may result in a longer than usual review time.
As previously mentioned, there’s increased review times recently due to v5 removal and CSP changes that have resulted in more Extensions being in the review queue. Hiring new staff and training them to handle reviews is not an appropriate solution for a short-term increase in review times (and keep in mind, 2 to 10 working days has been the standard since Extensions launched years ago, so this just the top end of the usual review times, and nothing that shouldn’t be expected).
Review times like this are something developers should be planning for in their release schedules if they have specific deadlines they must meet.