It depends on how retention interacts with other variables. I would argue that you can make exponential gains in things like product quality over the long term

It depends on how retention interacts with other variables. I would argue that you can make exponential gains in things like product quality over the long term by retaining a critical mass of experienced personnel, which translates to higher earnings etc. But yes if you view personnel costs as a line item in isolation and on a quarterly basis, you might not see those effects.