How to Measure Employee Satisfaction and NPS

The number one way that you can measure the return on investment for any investments in culture but particularly psychological safety is looking at how it changes the ability to attract and retain talent. I'm a big believer that psychological safety shouldn't be measured more than annually because you need to work pretty consistently to get at the core drivers of psych safety. And what's the frequency that you recommend for measuring that kind of employee satisfaction and NPS? Is it quarterly?