Autocalculate can be useful at times. mainly for when you have the enemy hopelessly outnumbered, or when the enemy has some nasty skills and spells that you don't want to deal with in a real time battle (i'm looking at you, ghosts). Autocalculate does not seem to take into account spells, skills and heroes. in This can feel a bit meta-gamey, as you can get positively slaughtered by ghosts in a real battle, but autocalculate lets you win with just some losses. On the other hand, i have had autobattles where i lost half my army while fighting the same battle for real lets me win with only very minor losses due to proper use of tactics and skills/spells.