Most times going out with a group, the bill ends up just being split evenly. I was not a fan of this, but often times, with friends, it's just a courteous thing in a way. You're all together, you're all having a meal or drinks. It makes it simple. And then, get what you want to get and not worry about paying more than you owe. That's what I started doing once I got older and our adult get togethers starting becoming more of "equally split" instead of everyone get your own bill.
Having said that, I would rather everyone just get their own bill. It's easy for them to split a bill or do separate checks these days, I don't see why not, but it's usually a group thing and the group usually seems to just want to split it equally.