Well, we have not always had (nor do we now have) a proper "dessert" after dinner on a daily basis. It is actually quite rare that I make a real dessert, normally if we are having guests only.
But, we do (often enough that it has become routine) have a little something (as Pooh bear might call it) after dinner. Mostly, because my husband almost always gets up from the dinner table, and within 30 minutes grabs a yogurt. We allow the kids to have something treat like after their meal, but they are older now and it isn't really predicated on how much of their dinner they eat, because, well, they eat without being made to.
An oreo or two. A scoop of vanilla ice cream. A chocolate chip cookie. A piece of pre-Halloween candy or two. A Little Debbie.
Any of those things could be "dessert". And the kids are old enough to choose their own. Half the time, okay, more than half the time, my son (who is 15) will ask what the options are and just decide he doesn't want any of whatever the choices are.
As long as they eat healthfully over the course of the day, I don't think it matters if they have a little something after dinner every day. It is kind of a reward for eating healthy all day, actually. Because, for the most part, they do.
I grew up in a home where anything sweet or "dessert-y" was a rarity. Jell-o was dessert sometimes and it was a treat. Chocolate was unheard of, unless it was in chocolate chip cookies (and those went fast in a family of 5 with 2 boys). So I basically grew up being "denied" any indulgence in sweets. I still have issues with it now, today, at 45. Because I feel like I am indulging in something forbidden.
I do not want my kids to feel that way. And they don't. There is almost always something around, and they never have that longing for sweets that never gets indulged. Total non-issue.
Daughter made herself a small bowl of ice-cream just a little while ago before she went to bed. (she's 12). Just a small bowl of vanilla ice cream. Nothing crazy. And she was perfectly happy. I don't have to go look in the freezer to see if she cleaned it out. She didn't use all the whipped cream and chocolate syrup in the house because nobody was standing over her watching and doling out limited portions. She has learned portion control over time..
When the kids were younger (like ages 5-8 or so) they got ONE cookie, if dessert was a cookie. Now, they can have a couple. And they will, if they are in the mood. Or they won't. But they don't raid the pantry and eat them all when they think no one is looking, either.
So, we use the term "dessert" for any after dinner treat. Whether it is a Halloween mini candy or a bowl of ice cream, or a slice of homemade apple pie or cheesecake. But rarely do we have the homemade pie or cheesecake. ;)
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So, per your SWH, as a final course of the meal, sitting at the table all served at once? Almost never. Thanksgiving, or if we have special guests over for dinner (not just extended family getting together). On those occasions I will actually serve a dessert course. Other than that... nope. See above.