Players set a threshold of how many units need to be involved on both sides in order to bring up the tactical battle screen. So it’s quick battle automatically until that threshold is met.
I would much prefer a different method of Auto Resolving.
With strategy games in the past, I have always given up on auto resolved battles, as about the most anoying thing is taking casualties in a fight you could have won better yourself. If there is a threshold, I will end up setting it to tactical battles whenever there is at least one unit on each side.
I'm especially interested in battles such as 'a few heroes vs an army' or 'an army vs a dragon'.
So, instead of making a threshold about how big the battle is, instead bias the auto resolve to deal with the battles that are boring. For each battle that is about to happen, work out what the auto-resolve results would be, and then, when the player is comitted to the battle, let them either accept the auto-resolve result (eg have a button that says 'win with 10% casulties', or 'lose with 80% casualties'), or to actually fight the battle themselves.
This way, players get to auto-resolve the fights that are prety much fore gone conclusions, and fight the interesting ones, where tactical changes make a difference.