Good article
@MustacheAndaHalf .
If you rebalance during a bull market, you sell risky assets that are rising faster and buy low-risk assets that are rising slower. Thus you get lower returns than if you'd done nothing. Call this type 1 conditions.
If you rebalance at the end of a bull market, you sell risky assets right before they fall. Thus you get higher returns than if you'd done nothing. Call this type 2 conditions.
Stocks are usually in a bull market and so more frequent rebalancing only helps if and when the losses from rebalancing during type 1 conditions are offset by the savings from rebalancing during type 2 conditions.
I.e. maybe you rebalance annually, and the next five years are destined to be four bull market years (+10% per year) followed by one bear market year (-25% that year). For the first four years, you move money out of the things gaining 10% per year, and into bonds earning 2%. Thus you are worse off than if you'd left them invested in those years. But then in year 5, you avoid a 25% loss on all the assets you moved to the 2% bonds. Do a spreadsheet, change the returns, and observe that sometimes you come out ahead and other times you don't. Quarterly rebalancing would work the same way, on a smaller scale.
My suggestion is to hold your semi-conservative AA until a bear market comes. It will eventually come, and you'll know it when it does! Take that opportunity to switch to your long-term 80/20 AA. By doing so you will have accomplished the practical objective of avoiding some of the damage from the first bear market close to your retirement time. EarlyRetirementNow.com's research suggests most failed retirement paths happened due to a market event within the first few years of retirement, and a glance at a chart of the
S&P500's total returns suggest that years of positive returns typically follow years of negative returns. So I figure why not just wait for that fat pitch. The tent is theoretically more graceful, and doesn't require leaping into the teeth of a bear, but I think my suggestion might work better against SORR.