Firstly, the stock market is concerned with how much profit businesses earn. Recessions are determined by changes in production. (Specifically, a recession is usually defined as a decline in GDP over two consecutive quarters.
That’s why it usually makes sense to just pick an asset allocation and stick with it, rather than trying to adjust your allocation based on events in the news. Conversely, it definitely can make sense to change your asset allocation when your life circumstances change.
Changes to the fixed-income side of a portfolio can make sense though, as economic circumstances change. That’s because current interest rates do give us some actionable information.
That is, the interest rate on a given fixed-income investment is a decent predictor of its rate of return (and it’s obviously a very good predictor, if you plan to hold to maturity). So shifting between fixed-income options as the available interest rates change is not crazy.