This is not a one-size-fits-all issue. Depending on the team, you might be able to write code that's 90-99% correct with little test coverage. Depending on the

This is not a one-size-fits-all issue. Depending on the team, you might be able to write code that's 90-99% correct with little test coverage. Depending on the problem space, code that's 90-99% correct might be good enough. In others, it might sink your company. You might lose 1% of "customers" due to bugs, but you could also easily lose 1% of customers due to bad copy or UX. Is that tested as rigorously as the code? Could the time you spent writing tests/specs have been used to implement and analyze A/B tests? Etc.