perhaps instead of increasing the cooldown, certain creatures could have a separate "storage" stat, that tracks how much they have of the substance. That way the spider can still rapid-fire webs, but if they do it non-stop they eventually run dry and have to grow more. Something like this would fit well with dragons, snakes, and maybe even fire imps, i feel.
+1 to thisThough i assume fire imp's fireballs may indeed be magical though, I could be wrong and there's some sort of sulphurous slits on their wrists that fire out like bombardier beetles as per a legitimate reason for the ability.
Otherwise logically speaking they should spread their web absolutely everywhere they go outside of combat and become feared by many underground creatures.
Their low cooldown also means that it could be exploited in fortress mode to produce silk on massive scale.
I understand that this current cooldown may exist to encourage the player into using different ways of defeating opponents such as rangered weapon but it does not justify [DIFFICULTY] of 3.
Though keep in mind, unlike the dragon, its more than likely not the webs that actually kill the adventurers but rather the large mandibles the GLS pushes through the poor-sap's cranium while they're held perfectly still to try and guratee a bite, which can be blocked by a simple iron helmet & bringing companion friends to micromanage your party. I dont think every DF monster should be fought alone without least comprehending the risks to going alone in adventuremode (something bogeymen gently coax people towards even if they've recently took a backseat) but i can see the frustration such a early monster as a GCS can give new players.
Its like being beaten up by your first Hovertank/Mi-Go/Jabberslythe in CDDA and other roguelikes, its certainly "doable" alone if prepared ahead of time.
Storage makes more sense to me though, with some added logic it could be added to the bodypart organ logic, as at the moment emission is only (sometimes) dependent on something arbitary like saying "it comes from the mouth" and nothing beyond that as most emissions just culminate out of thin air. Being able to butcher the web out of a giant spiders abdomen with tokens for a retrievable resource would be good, add more extracts by having a storage for their venom so we can finally have a "big animal dissector" draining off the contents, or yank the dragon's firebreath organ whole from the butchery station as a alchemical ingredient would be much appreicated.
Though i guess the simplest would be not storing things like milk in a cow's body-detail on a purely animal token based level and moving it moreso internal. No-drop, embedded lower body, milkable udders being a simple tag combo to keep things as they are.