Oh yeah, they will follow you.
I had to abandon my vehicle after driving ~50map squares SW with a horde following along behind me and updating their point of interest sporadically with my location as I drove (in the dark, with only 1 headlight driving a 75% loaded 3-wheeled armored troop transport I had just found in and managed to break through the double-rock wall of a hazardous waste receptacle) when I started to attract the hordes ahead and to the north of me.
I veered off onto a side street that eventually led to a farm and tried to be as quiet as possible with my whatever-ton truck.
I creeped into the farm and, after eating a heartyily disgusting mre, was planning to hole up for the night when I spotted a shocker zombie from afar.
Abandoning the farmhouse seemed the wisest course of action as I had managed to scavenge a couple of weapons but only ~two clips of 9mm bullets for my mp5 and along with possessing only a newly acquired, and still unfamiliar, combat knife and aching torso damage, a horde of zombies was not looking very palatable.
I jumped into the truck, flicked on the remaining dimming, cracked headlight and started circling back the way I came as the night erupted in shuffling zombies surrounding me from all directions. I plowed through a few of the undead with the remnants of my spiked armor yet before I could get back to the main road encountered another smaller horde.
I was forced off the road unless I wanted to risk looping back around the way I had originally came and drive through the center of the huge horde I had just fled. After a few minutes of off-roading I encountered another road, drove a short distance and ran into the beginnings of a city or a small town, it was too dark to tell which. I abandoned my vehicle there as I could debuggily sense all of surrounding hordes still attracted to the sound from my engine or my headlights and stumbled through the forest for about an hour before I was able to circle around the initial horde I was fleeing from and finally access the military bunker, LOE shelter and town NE of my starting location I had noticed while fleeing from the horde that surprised me right outside my initial shelter.
The hordes seemed to have an ability to detect noises/ lights from at least a 10-15 square distance from the edge of their blue border in debug - maybe it is dependent upon the red +?
If there were 3x more hordes, but they were a smaller (denser too) it would be a little more manageable, in my opinion.
Or utilize the z-from-b-origin in the canon to its fullest and state that each horde is controlled by its own b consciousness, or some such, which is exerting its influence over said horde area. Each b consciousness is able to generate (technically reanimate the long-buried dead) within its sphere of influence. This would result in mostly skeletal zombies (or skeletal animals in the wilderness) and should probably be accompanied with another branch of z-b evolution to mostly skeletal creatures. (But probably at that technical point in b-reanimation it would be easier just to grab a bunch of branches (Zombie Trees?!) and rocks and use them as body-structures then it would be to create a whole musculature/ locomotion system from nothing around a frame - maybe include a numDeadBodiesBuried per mapsquare and after all dead bodies in a square have been reanimated the horde can only generate blobs or make, I dunno, rotten tomato creatures or something)
For some cool ideas on hive-mind creature-societies and interesting mechanics check out the Commonwealth Saga by Peter F. Hamilton. I have a love-hate relationship with that guy and his stories, but the alien antagonists in those books were truly awesome (as long as you can overlook the mystical-magical-from-the-beginning-of-time-elves aliens who live on magical spirit-journey find-yourself,finally-planets and al capone’s criminal space empire).