Every damn endeavor I ran, specially the book ones... I just can't keep it simple.
Here are some examples:
The one in the Egarian Dominion which was the one I screwed up the least, started with a "starship troopers"-style battle which got 1 PC to use faith in the fourth round, and ended up with a dogfight between bloodflayers and fury interceptors while a Mauler kept the player's ship away from the moon.
"Into the Maw" involved "dead space" exploration with ebon geists in the Righteous Path (RT PC lost an arm), and some crazy mannouvering in the asteroid field against Hadarak Fel's upgraded Light Cruiser.
The Lure of the Expanse derailed so much, the PC's Dynasty broke financially before they got past the Light of Terra (check my posts in "Tales of Glory" thread) and by that point, 2 RTs were already dead and another one was captured. 2 PCs dead.
Am I doing it wrong? Are the challenges that harsh? Should I keep it simpler for faster play and more rapid evolution of the PCs and PF?