How often should you run employee surveys?

A workable rhythm for a company of 100 to 500 people is one full engagement or climate survey a year, a pulse survey each quarter, eNPS monthly or quarterly, and lifecycle surveys on trigger: onboarding at week four and exit within the notice period. The real constraint is not how often you can ask, it is how often you can respond. Do not run a pulse survey more frequently than you are willing to publish results and act on them, because a survey that produces no visible change trains people to stop answering honestly.