Would be nice if we could just use something like the Vanguard Target Date Fund asset allocation as a preset for bonds.
So how would this work? You’d figure out the starting stock/bond allocation based on the age of the person. And then model out based on that?
In the case of a couple creating their model, you’d want to come up with some kind of average age between the two?
The TDFs have predefined allocation timelines based on the fund. It could be that it’s taken into consideration when the account’s TDF is specified. Nevertheless this would open a whole new door of complications and a standalone project. Many investment portfolios contain multiple funds it would have to be very granular and updating constantly in real-time with balances etc… I wouldn’t go there
It would be great to compare some very basic glide paths such as Age in Bonds, Age - 10 in Bonds, Age - X in Bonds, Target Date Fund average glide path (should be default I think), “Lifecycle Investing” glidepath. I think there’s some deep threads on the Bogleheads forum getting into more esoteric glide paths.