I don't recommend things that I don't know works by having tried it myself. Extending development time 'generally' (as I said earlier, generally), will develop the shadows more, increasing film speed. I have never seen base fog increase visibly, and nowhere near the increase I've had in shadow detail. Without step wedge.
Xtol, D76, Rodinal, Pyrocat, DD-X, HC-110, and Edwal 12. With FP4+, TMY, TMY-2, TX400, HP5+, Delta 3200, TMZ, TMX, Acros, and Neopan 400. That covers many films in production today.