There was a time when candidates would get stuck on a problem and I would tell them "if you want, keep working on this problem and email me tonight with your work." Most people didn't follow up, but some people did, and we usually hired them. They usually had very high grit and follow through, but were unfortunately (as a rule) slower and generally worse at their jobs than other hires. We had to let one of these people go despite his excellent communication and organization skills. Today I can rely on a stronger recruiting pipeline so I don't need to make exceptions like this, but I'm not really sure if I would go back given the chance.

No matter how much grit you have, if it takes you 10 hours to do what everyone else is doing in 1 hour, you will struggle _a lot_ at your job.