I've always used very young dragons as generic fodder, for as long as I've been running games. Given that a dragon tends to die whenever it shows up, I figured there must be tons of them out there, for any of them to survive to adulthood.
Huh! I never use young dragons as generic fodder because my assumptions are the exact opposite of yours.
See, my default headcanon for dragons came from Shadowrun which I was exposed to before D&D, so all of my assumptions are the exact opposite of what you just said. I see adult and older dragons being genius master manipulator archmagi whose physical status as fire-breathing flying dinosaurs is often a last resort. Dragons do not have babies like a frog releasing tons of tadpoles hoping a few will survive, they generally have one egg at a time. Wyrmlings are incredibly rare and precious and virtually never unguarded; wyrmlings that are orphaned are sometimes fostered by other dragons (in the first session of my most recent now probably dead campaign the PCs killed a wyrmling green dragon, actually pretty impressive because there were only two of them that session and they were 3rd level; anyway I later worked out that green wyrmling was being fostered by the young black dragon in one of the other caves of chaos). Killing a wyrmling is the single most reprehensible thing you can do and is the surest way to bring all dragons in the area
With the exception of the huge swathes of the original Dragonlance campaign that I ran for my ex in 3.5, where dragon death was not uncommon, particularly not once the PCs actually started arming themselves with the titular
dragonlances which are
really quite good at killing dragons, unsurprisingly...anyway, in all other D&D that I've run, dragons virtually NEVER died when they showed up. I don't mean because dragons in 3.5 had the [Awesome] subtype and I love to TPK my players--I just play dragons as extremely smart and extremely focused on self-preservation (assuming it can reasonably have the spell, the first turn I take with any dragon is casting Protection From Energy specifying the type it's vulnerable to). My thinking in that case is that dragons wouldn't live to be thousands of years old in a world where everyone wants to kill them for their valuable body parts and ample treasure if they were not incredibly careful.
Likewise, I have had dragons 'flee' fights while they were still at hundreds of hp. Sometimes, granted, the out of game reason for this was to keep all my players from winding up in the dragon's belly, but the in-game reason was always that the dragon has a lifespan of millennia at stake--with that much to gain, and with time on your side, why take any chances? Of course I have roleplayed some dragons that were stupid or reckless--this was
specified in some cases in Dragonlance--but generally speaking I play them crafty and cautious.
Other idiosyncracies of my use of dragons: I have never been a believer in the idea that all chromatic dragons are evil or that all metallic dragons are good. Crazy, right? But I dunno, the idea that someone can tell whether you're a good or bad
person dragon just by looking at the color of your
skin scales never sat right with me. In spite of that though, funnily enough I can't think of an instance of my ever actually having used a nonevil chromatic or a nongood metallic in one of my campaigns. But they're there!
OUT OF CURIOSITY: was anyone who picked either the first or last option on the poll NOT joking about their vote?
Someone mentioned the Underdark as being one place there were no dragons, and someone else mentioned there being no dragons on the plane of Ravenloft. I feel like there would be shadow dragons in both of those locations, since the Shadowfell touches the Underdark and I presume the plane of shadow has links to Ravenloft.