Depends on the type of work, surely. If it's menial tasks and labor is plenty, you can afford your workforce continuously burning out, since it's fast to train and easy to replace. It's exploitative, but as long as it makes the market happy...
For highly-educated jobs where people need 6 months of onboarding and institutional knowledge matters, it's probably more efficient to reduce churn.
For highly-educated jobs where people need 6 months of onboarding and institutional knowledge matters, it's probably more efficient to reduce churn.