Also, there's sense in using a single angel to clear a lot of maxmen, for instance, because on quick combat you can clear a huge lot with a level 0 hero, but on tactics, if you fight, there's a high chance of wiping. But there are no miracles here either, and say, a horde of maxmen cannot be defeated by an angel of a normal level 1 hero whether on quick or on tactics..
And then there's the long-known trick with hydras. Other than that, there are no more advantages to quick combat; in the vast majority of cases, the computer conducts the fight much worse than you would, preserving all sorts of useless trash while losing strike stacks where nothing should have been lost... (I wrote a more detailed hypothesis on Bay as to why this happens). So what's left: fights in the first days of the game with shooting units against shooters with fewer shooter losses than if you fought on tactics (but even here, not always, and miracles like clearing a throng of maxmen with archers on day 1 starting as Castle won't happen; the battle is won in most cases even if fought on tactics, but on quick combat, far fewer shooters are consumed), and next—fighting with one angel against a lot of low-level shooters (maxmen, archers, gogs, lizards...). This isn't exactly a feature, as you'd likely clear them on tactics too (though you might wipe, whereas on quick combat you won't...). But if you risk it and attack a horde of archers, and it turns out to be large, the wipe will happen both on tactics and on quick combat, except on tactics you can retreat if you need that hero, while on quick combat, you can't. As for hydras—I believe there's no crime there; taking a hive with one hydra is genuinely useful, but few would risk various experiments with utopians etc. in a real game, because with 6 hydras and a decoy, you can break a utopian anyway, whereas it's completely unclear how the stupid computer will behave—because if you use a decoy, it will surely conduct the fight worse than a human, and if you use one squad of hydras, as I understand it, there's no guarantee they'll take one utopian, and in case of their loss, the utopian can't be taken even with the remaining trash on tactics (or it can be taken, but with losses much greater than with a hydra...). While playing SoD, generally, no one uses quick combat—why bother??? (time doesn't pass during battle...). (Unless it's the very first games with shooting blocks and strike units that are also shooters...). But in TE, you have to use it, and very often—not because life is good, but because you fall into a severe time crunch, and you hit weaker neutrals on quick combat, although sometimes tears come to your eyes from the stupid losses the computer makes, which wouldn't happen at all if you fought yourself... (like me: I attacked a horde of zombies with a level 10 fighter hero, a ballista, and an angel on quick combat in TE and... lost the hero... It's still unclear how the computer fought for this to happen, because after the game I conducted this battle on tactics—it was won while preserving both the angel and the ballista, and the angel was quite healthy, but on quick combat... (though it's obvious—the angel immediately flew forward to the zombies without waits, right into the thick of it, was surrounded by all stacks and beaten, and since the horde was maximal, the little angel was eventually killed off... )