Please help with finance question. Thanks

What judgment would you make about diversification during an economic recession? An economic expansion?

Diversification of investments is always the best policy. Trying to "know" what investment type to be in and when to get out of it is impossible for most people. That includes equities, bonds, commodities and cash. Out-of-favor sectors tend to be oversold, and "hot" investment sectors tend to be overbought as the "greater fool theory" operates.