Do any of your organizations have a flexible time off policy in place instead of a PTO or vacation bank?  Essentially empowering employees to take when/if they need it, still track it and within guidelines, but no rollover, payout or otherwise except where required?  If so, would you be willing to share general info like company size & industry, how it was implemented and received, etc...

We have both set PTO for individual contributors and FTO for leaders.  The FTO for people leaders works very well. We have recently had to add a separate sick time bucket for state requirements (I would highly recommend this) as they are constantly evolving.

We do and it works well for us.  We're a smaller tech startup (~150 employees), about 80% of our employees are fully remote and we have folks in 31 states.  We have a policy that requires advanced notice/approval, so it's not a free-for-all.  And we're very careful about using the word "discretionary" versus "unlimited".  We do not offer unlimited time off, and we've found it helpful to provide guidelines around what is "typical".  The things I'd call out for you to consider as you determine whether this approach would work well for your organization:   

1.  I would strongly recommend maintaining separate sick time policies so you can ensure you're complying with State laws that require it. 
 
2. Monitor usage to ensure employees are actually taking time off.  I'm sure you've read articles & research around policies like this having the opposite effect of employees taking LESS time, so keeping a pulse on usage and making sure people are taking the time they need to disconnect will go a long way.  

I hope this is helpful but happy to connect if you have additional questions!  Good luck!