Dexters are smart, and each have a personality. You have to know your own Dexters in order to judge what's safe and what's not.
I think it's hard to beat a family herd. That is one where most of them grew up together and know each other intimately. The pecking order is firmly established and most problems never even happen.
When we introduce new Dexters to the farm, it's up to us to train them. Once they accept our training, they are better than our children at following the rules
In my herd, the bull is the second most respected animal, right after me. He has his own place at the feeder, his own place at the haybale and his own place to sleep or loaf. The others may sneak a bite from his place before he arrives, but once he gets close, his place is open and waiting.
The herd leader is the oldest cow, or the biggest cow, or the one with the strongest personality. Maybe all of those. She actually runs the herd. She decides when they will move to another spot to graze, or when they will head for shade to lie down and cud. When you see the cattle moving across the fields, she is usually the one in front.
All of the other members have a rank, and every one of lesser rank has to yield to the higher ranked Dexter. It helps a lot if you know this ranking. Trying to feed a low-ranked cow before a higher ranked cow can cause trouble. Don't try to change the rankings, just know and follow them.
I really enjoy watching the young calves learn their place in the herd. You can almost predict that the offspring of the herd leader will attain a high ranking. They learn from observing their mothers.
Horned and polled are not the final determinators of rank. I once had a horned Dexter and a polled Dexter-cross cow that traded places as herd leader, based upon who was the most pregnant!
The polled cross went to another farm where she has been the undisputed leader of her herd for years, now. Her herd-mates, including her offspring, have been a mix of horned and polled and it has never seemed to make a difference in their place in the herd rankings.
Interestingly, he added two fullblooded Highland cows to the herd, a mother and daughter. They were terrors and used their horns wickedly. He got a Dexter/Highland cross heifer out of each of them and then dispatched them to freezerland. The daughters, both horned, have been super sweet and have produced many sweet natured offspring. We give the credit for this to the overall gentle nature of the Dexter blood, taming the wild Highland blood.