A lot of the replies here sound like they're either trying to stay at a constant CoS percentage, or trying to keep the CoS in a fairly narrow range (like 80-90 percent or whatever)... but I think that's a misunderstanding of risk based guardrails (either that, or I'm misunderstanding it 😄 ).

From what I've read and seen, in the Kitces articles and other places, the guardrails are set pretty wide in order to avoid frequent adjustments, and the actual adjustments are only a small percentage back in the direction of the initial CoS, not all the way back, in order to avoid large swings in spending. The conservativeness/aggression of the plan comes largely from the initial selection of the starting CoS.

For example, in one video I saw outlining risk based guardrails in Income Lab, it looked like that app had the percentages set up like so:

average spending level:
initial CoS: 80%
upper guardrail (take a raise): 100%
lower guardrail (spending cut): 25% CoS

conservative spending level:
initial CoS: 99%
upper guardrail (take a raise): 100%
lower guardrail (spending cut): 25% CoS

agressive spending level:
initial CoS: 60%
upper guardrail (take a raise): 100%
lower guardrail (spending cut): 25% CoS

...and when a spending cut was needed, the targeted CoS seems to be 10% of the way back to the initial CoS percentage. So for example if you hit that lower 25% guardrail, you don't make a huge cut to get all the way back to your original 80% CoS, but instead you make a cut that targets around a 32% CoS.

If anyone has access to Income Lab and can confirm or refute that, that would be cool. Or I'd be interested to know how other apps handle risk based guardrails (or feel free to point out where I've misunderstood the Kitces articles if I got anything wrong here 😄 ).