>>>>It sounds like your real time example also includes further contributions. That would complicate matters. It sounds like your method does a good job of anticipating that. <<<
Typically I would use the new contributions to rebalance with
In my friends case I knew new money would be added every year and last year instead of possibly selling some stock I assumed the next IRA contribution was already there. Last month when I looked at it for the annual rebalance it was almost perfect for where I wanted it to be.
I will look at it again in a year.
Eventually I want to put the cash in to TLT (when rates are higher) but I will sit on it for now.