Asset class inputs effect on Roth conversions

I started my plan at the beginning of 2025. I am using the following asset classes using custom rates of return and standard deviations for 2026. I have it set for advanced portfolio managing mode 2. Do these values seem reasonable?

For 2025 I entered my existing asset allocation for my targets since I knew I would slowly balance my portfolio of the course of the year. I now have my account balanced to meet my long term allocation so I plan on updating the targets for 2026.

The first time I ran a test Roth conversion for my newly balanced portfolio the results were way different than I expected compared to 2025. I then made the listed changes to the rates of return and standard deviation and reran it. The results are completely different again.

I now see how much a change to the inputs can make the results change. How does everyone handle this? Do you update the inputs each year?

My real plan was to just fill my 22% tax bracket each year until my RMD's start. I am using the Roth conversion analysis as a high level check to see if my plan makes sense year to year or to see if I should further limit my conversion for IRMAA steps.

My rates of return are nominal and I used 3.5% for inflation and a 2% adder for healthcare costs.

I run the Monte Carlo with correlated rates on and off plus I run historical for a few different scenarios.

The Roth conversion calculator doesn't show

Rate of return

Standard deviation