One of the great things about the market today is that there is no shortage of material for your favorite D&Dish game. Whether you're playing D&D 5E, Pathfinder 2nd Edition, Labyrinth Lord, Swords &Wizardry, Old School Essentials or literally dozens of other variants, retroclones and heartbreakers there's both a system to suit your needs and a mess of scenarios to make prep easier.
While perusing a variety of recent finds I have been enjoying, for their own purposes, a range of modules....but these modules are not all created equal. For example, Trilemma Adventures is arguably a huge bang for its buck, with dozens of scenarios wrapped in a setting and bestiary suitable for adaptation to your preferred system. Age of Extinction, by contrast, is a pricey six book series for Pathfinder 2nd which will get you close to level 20 albeit through a process of reading an elaborate campaign in Golarian which is exceedingly difficult to adapt to your own setting (and likely not worth adapting to other rules systems).
Still...taken as a whole the typical Pathfinder adventure path may look huge, but they are designed to be digested in six discreet pieces. Not so with most WotC modules, which are monstrous incarnations of mega campaigns. When you buy one of these you are getting everything including the kitchen sink in one gigantic purchase.
In many ways it seems like the conventional wisdom for D&D and Pathfinder in their contemporary editions, the pinnacle of achievement over the last two decades, has been the extensive long form adventure campaign. Most of 5th edition's published modules amount to lengthy campaigns, designed to provide structured frameworks for leveling up to 10th level or greater. Only a few adaptations of older works such as Tales from the Yawning Portal focus on smaller scenarios (and even then providing a framework to interconnect it all together). The only one of these I've run was the early release of Siege at Dragonspear, a level 1-10 romp in four parts.
I don't really understand this style of long-form adventure design. I am much better with (and can appreciate) a good setting book such as the Guildmaster's Guide to Ravnica (well, as long as the book is engaging and fun to read, which most sourcebooks are not). I get more out of the content in Volo's Guide to Monsters than I do out of the latest 300 page super module. I suspect I am not alone in this; for many who GM, the creative process is more rewarding and may be the key reason to play; but there are many who enjoy reading and puzzling out these giant modules to provide much needed direction to their group and games.
Products like Trilemma Adventures, of which there are lots and lots of examples (from Dungeon Full of Monsters which flirts with being both mini and mega to AAW's Mini-Dungeons series on down to Dyson Logos' amazing collections) are designed to provide tools to a different kind of GM, the kind who likes improv and needs only a seed to grow a mountain. Plus, if you like campaigns that are deliberately less structured or more focused on hexcrawling then mini dungeons and short-form scenarios provide plenty of content for populating your wilderness without also committing to memorizing hundreds of pages of content.
The fact that the market is so well served on all fronts right now is a good sign. Most short-form and mini adventures are coming from the indie, OSR and small press side of the equation, but an argument can be made that even Paizo and WotC know there's a market (just not one worth chasing beyond a limited set), and their respective Pathfinder Society and Adventurer's League modules may actually cater to some degree to this market (and not just organized play).
That said....once again I'll toot the horn for Goodman Games, which has built an entire business structure on short-form modules (with an occasional long-form gem like The Chained Coffin) and of course putting an emphasis on making them eminently readable and fun. Like with my prior article, the notion of readability and the even more important factor of being Fun to Read is extremely important to modules, and if someone were able to collect more than anecdotal evidence I sincerely believe we would find that the modules most played are, on average, going to correspond the modules that were the most fun to read (and well-designed too, no doubt).
Ironically, Goodman Games is also responsible for one of the most interesting cases of short to long form design you can find: the Original Adventures Reincarnated Series literally take the classic modules of yore and, under license, adapt these short form gems into modern long form designs. Yes, they can take a 32 page module like The Isle of Dread and turned it into a 200+ page adaptation (while somehow still being the original module, a feat in and of itself). If ever there was a better example of how the short form module contrasts with the long form, this is it.