10mo
Thank you for your feedback. Fair that familiarity with the stack really helps here.
For context, we hire contractors who can jump right in, and most contract work assumes prior expertise. We get 100 applicants per role on average. Of those who get to the take-home exercise, few put in as much effort as you said here - 30 hours. We've hired folks after 4 hours on the take-home exercise, and more commonly we hire ones that put in more time. 30 hours tends to be on the very high end though. I do not have metrics on the average time spent for hired folks, but it would be interesting.
The take-home has options for various languages, but oftentimes we expect specific ones for a role we would hire. We are working on making it more accessible to submit a passable take-home, but we have a fairly light interview process so our take-home is really the primary way to show expertise (and the best, IMO, in software engineering technical skills).