I'm obsessed with fort entrances and defense, to the point that I'll ignore everything except beds, tables and chairs, and stockpiles in favor of wasting time preparing mechanisms and traps and digging channels and smoothing ramps and collapsing layers to create steep walls, and usually end up invaded before I complete any of it
Working on just setting up a small interior defense (a drawbridge would do) before starting on the bigger stuff..
Last nights failure was a heavily goblin-and-undead-infested reanimating biome where I channeled out the entire flatland to let the water expand all the way back to sheer walls, leaving only three single-tile straight paths into my fort, all three of which were designed to have a very long shooting range for a catapult-based defense.. The zombs showed up just as I built the bridge and linked a lever (the guy was there attaching the mechanism to the bridge when they showed up less than 10 tiles away and
he actually finished attaching them.. Almost never happens!)
Anyway, they ate me alive and I didn't even have catapult parts built or stone piled nearby to power them.. 5 survivors, two of which are in the hospital (one with a broken toe only), two of which are children, and the only one that'll listen to orders at all is the expedition leader.. I've locked the kids away and he
might stabilize..
Also, dependance on Therapist is pretty terrifying, considering the changes coming in the next update :| Sad part is I only really started using it with the last update, and only to quickly pinpoint the highest-skilled dwarf out of my 150+ to assign personal workshops..