Congregate is like aggregate. These are situations that occur among social animals. Social Animals love to congregate and aggregate, that is they like to huddle up and get close to each other. They also love to congress with each other, as do even a-social animals. But congressing is another story for another time.
I would not recommend either congregation nor aggregation in our time. (I am not sure I would recommend congressing either—but, as I say, that is a different story.) The reason I would not recommend aggregation or congregation is guns. When guns go off they are much more likely to hit flesh and bone if those fleshes and bones are attached to social animals in congregation or aggregate.
This is especially a possibility when a gun operator intends for the gun to go off. It is less likely a possibility if the gun operator does not have intent—but it still happens. If things are elbow to elbow, nose to nose, butt to butt, (a real aggregated congregation) when a gun is operated, whether intentional or not, things can get messy. De-aggregated brains, guts and blood splatter on other congregants, who may or may not have brains, guts and blood that are still aggregated. Also, hearts get torn from those social animals thinking about congressing, which causes ache and hurt.
As for congressing. I wouldn’t recommend that in our time, either. Because. When social animals congress, they make more social animals. This means they are more likely to congregate. It also means there are more of them to operate guns. The results are obvious. More congregations aggregated together; more guns get operated; more brains, guts, and blood are splattered. Which means more congressing hearts are not congressing any more, anyway.
So don’t congregate. And have fun with that.