as of update 34.1 followers seem to have increased aggro, meaning they detect a zombie from a mile out and rush towards it to kill it. Frankly - it's extremely annoying because they often get in the way and steal your kills (they don't improve their fighting skills while being a follower, right ?). I usually just go out solo to avoid this nuissance.
Many games with NPC followers offer dialog options that allow players to influence their behavior - for instance you can order an NPC to wait or keep close. It would be great to have simmilar functionality in SoD2 : you're tired of a follower rushing towards the nearest zombie to put it down ? Just order them to stay put until you clear the area ahead so they can resume being a mule.
If such functionality is too much effort / resources (it shouldn't be - just one or two additional dialog options and some minor tweaking under the hood) - please just dial the followers' aggro down so they wouldn't make me feel obsolete when facing one or two zombies.