Let employees earn the ability to take a low-pay sabbatical once they get an itch to leave and/or burnout. Companies make extended absences work for parental leave, so just do that for more people more often
There is an available option for this: FMLA. It can be difficult to find a doctor to sign off, if you haven't already been in therapy though, which is unfortunate. When you realize you're burned out, it's usually past the point where you need a hand. FMLA doesn't guarantee salary but it does require that medical coverage is maintained and that your job is safe. SDI can help with income, which is why you need a doctor involved.