The Trouble With Lairs
Lairs are distinguished from megadungeons in that they are the abode of one singular organized body. Key thing here is that many players aren't used to fighting something organized. Many of the PCs around my version of Yggsburgh have had their worst runs when invading lairs. Whether the lair was the Pod Caverns of the Sinister Shroom or my own 'Kobolds of Ever Winter', they've had runs against lairs that should have ended adventuring careers, even for those that survived. Many of these runs were losing propositions, where they used up in supplies and expendables many times what they were able to pull out of the dungeon. Sometimes you 'eat the barr' and sometimes... It's the kinda thing that aught to drive them to find megadungeon type environments where there is more exploitable chaos. And that's why I run sandboxes, so they can choose their preferred level of risk and reward. I shouldn't be too harsh on my players in this post.