First, think of a culture that's left structures peppered around your game world. Let's pick Dwarves. Second, decide on some features their strongholds/outposts almost always have. Let's say:
- cave fish pond
- ore storage
- smelting room with chimney
- throne room
- hidden gem storage
- secret emergency exit/bolt route
Then you should be set for the next time players go off map or an encounter roll calls for creatures to be in lair. You pull out your stack of stencils for Dwarven Outpost (you can keep different types bundled with rubberbands) roll dice, or shuffle and draw the cards, then trace them on your graph paper. It might take a few minutes but you'll have a consistent dungeon with a map for your campaign folder.
If it works as I imagine players could learn things about these dungeons that would add a sense of verisimilitude to the imagined world: "Wait, this looks to be a Dwarven outpost, they almost always have a secret gem room." Or "These Dwarven outposts tend to have smelting rooms with chimneys, so we might find a small but definite exit to the surface there."
If the stencils work as I hope, the next design challenge would be to make sure all of your recurring dungeons have features that players would find interesting, like the examples above. maybe cultists have libraries, outposts of the old magic-rich empire always have a brass head mounted somewhere, and tombs of the old empire tend to have map rooms with a diorama display of the surrounding countryside (and the location of more tombs).
(I plan to try to actually produce some of these but I'm currently house sitting for friends so it may be a while.)
Update: I had a hard time titling this, Procedural isn't right. I think I probably should have called it Template dungeon (but that sounded kind of boring) . Oh, well. That makes me wonder what a true DIY procdeural dungeon would look like, too.