Can a grandmaster still win against engines if they have a really long consideration time? Can a grandmaster still win against engines if they have a really long consideration time? For example, say that Stockfish gets 20 minutes and the GM receives days, if not weeks.
Are there asymmetric time controls where a GM can still beat Stockfish? Certainly, as long as you give Stockfish little enough time. I think the time you give to Stockfish is almost more important than the time that the GM gets. At 20ms I would favor the GM even at tournament time controls.
A few years back I played a handicap game against Komodo where I played some blitz time control (maybe 5+0 or so, I don't quite remember) and Komodo had 1 second, which should work out to roughly 20 ms per move and I think back then I could actually win that game. Since then engines have progressed so modern Stockfish is probably 300 rating points stronger than the Komodo from back then, but on the other hand I am more than 300 rating points below a GM so I would think the GM should have chances even if they blitz, nevermind at tournament time controls or longer. As it turns out engines aren't really made for 20 ms per move games so they don't perform very well there. Now if you give the engine a second per move things may be very different.
As a fun experiment you can just try yourself, give yourself sufficiently much time against Stockfish and give it a go, see how it goes.