I'm familiar with Graham's "net net" approach, but I have no idea how to actually find such companies. Just read a bunch of SEC filings?
Nah, way easier. :) Find bulletproof companies with huge moats (like, say, XOM or BA, or travel stocks), do some DD on them to make sure they're not run by complete sociopaths and don't have toxic debt obligations, put them on some Yahoo Finance watchlist or some such, then do like a lizard and wait... If at any point in time the market falls like it did during the first half of 2020, and if those stocks go on sale, you just dust off your DD, confirm that they will not, in fact, go out of business, and then swoop in and buy them up. Hell, even Disney fell below $100 - that's just free money right there. :)