I’ve been to houses where there are 4 kids and even though there’s plenty of food, the kids all grab and worry they will miss out, especially when it’s treat food or pudding.
The result of this, in terms of someone serving food or serving bowls with a help-yourself approach, is that they all snatch and take. Ore than they want or need, often to stop someone else having it. Clearly this is a problem in the household and needs to be managed and decent behaviour taught, rather than being an issue with the food itself.
Personally, I think it’s good for people to wait for 2nd until everyone has had firsts. Especially at cHristmas when there can be lots of people, those served last might have barely started by the time others finish, if the arrangement isn’t that people wait until all are served. There’s no reason why those served last would like seconds any less than those served first, and if seconds are help yourself at any point, or someone offers them when some have just started, unless there’s enough for all to have seconds, not everyone will get an equal chance of seconds.
Ideally, serving up is done quickly so people wait to eat until all have their food and everyone starts eating at once. This means the food hasn’t gone cold and eating is a communal experience. This last point is the key one - eating is a communal experience. When people feel they can gobble their whole meal before everyone is even served, or take seconds, finishing off what is left before everyone might even be ready to consider if they’d like extra, the communal element is lost. Instead of it becoming about eating together and enjoying the food and company, and considering others (aren’t most people taught not to take the last roast potato for example) if it becomes about gobbling as fast as you can and having as much as you can personally shove in, without consideration for others and what they might like or about eating together, something major has been lost.
Yes, very small children might find it hard to sit through a long meal. Slightly older children might not have been taught to wait for others before starting, or not to demand seconds or to only think about what THEY want, but also some adults remain in this position. There can be a rather surprising lack of manners I think.
Hosts can help with all this. Getting hot plates on the table, directing people to start helping themselves and serve each other as dishes appear, can speed up the serving. Slowly bringing out dishes of food one by one and no plates to serve onto until everything is out and going cold, really doesn’t help, or encourage others to wait until everyone is served. Neither does waiting to serve until everyone is absolutely ravenous, or having tiny amounts which leaves people worried they will be hungry and prone to grab, before it’s all gone.