James, In those studies, they had to make a lot of assumptions. One of them was to rebalance annually. Not because it was the right thing to do. But just because they had to assume something. As you know, computer demand that sort of thing! In the real world, rebalancing might have been completely the wrong thing to do. At end of each year investors would have decided.And all of these assume the classic AA, meaning rebalancing to hold a steady allocation.
In the original study, you are right - the AAs used were nor arbitrary. They were specific - 0%, 25%,50%, 75% and 100%. 50% equity worked best, but then they found that 75% was just as good. But really, what do those numbers really mean? The exact same portfolio could change, for example, from 60% to 40% or vice versa if you just started the study a year earlier or later.
I had some trouble with the term "Classic". I have a couple of Classic cars. There is a definition of Classic for cars. I know financial industry people use the term classic, but does it really mean anything at all? Maybe just sounds good when selling a product?
Anyway, snowy day/night here. Time to go read a book