Every downturn is different on both a macro and local level.
I do not know how raw land did, but San Diego county homes suffered around 20% decline in the Great Recession (GR). There were areas that suffered worse. Valley Center had recently completed a large residential community that had issues finding buyers. It drove the entire area down more than most other areas. However, the area where our rentals were located suffered no noticeable decline in rents. People moved into high occupancy living situations but the banks had so many empty units the supply and demand stayed fairly level.
The 1987? stock crash was a few years before I purchased our first RE, but I do not remember it resulting in a significant RE price decline but I was just graduating from college and could have simply been unaware.
The Dot Com bust (circa 2000), in the local market, had RE prices rising. We purchased a great RE in 1999 that had enough appreciation (mostly market appreciation but a little value add) that we were able to leverage it to do 2 additional purchases (I think both in 2000 but one may have been 2001).
The issue with the GR on taking advantage of the price drop is that money became scarce. Only wealthy investors could get financing to take advantage of the situation. So a lot of the wealth to be made on the reduced price was by housing corporations and some by REITs. If you cannot get financing, it is not easy to buy much RE.
To summarize, down financial markets have not always resulted in down RE markets. I suspect the same is true of raw land. The one time in my RE investing life that the down financial market did result in large declines to RE prices, the scarcity of money made it difficult to take huge advantage of the situation.
Good luck
