My experience was the remaining walkers and last abomination spawned on the same turn, so they came out pretty evenly. I seem to always get non-stop Abomination spawn though. Didn't really find that map hard, but obviously the cards and dice have a big impact on difficulty.
I can see how, since you need Molotov's to kill Abominations (or Tiger Sam's "+1 damage: ranged" skill) having them spawn more frequently could be a problem. Think maybe you just saw the extreme end of the random spectrum.
Main thing I noticed, that map/mission is a zombie shooting gallery! Had one survivor that was going to hit the red level before I could open the blue/green door (note - you only have to open one of them....unless you really want five spawn zones), so at that point I just camped in the middle of the map and went on a killing spree until everyone was in the red, had spun the level meter 3 times, and had all seven of their skills (was using the Ultrared option). Think I killed nearly 500 zombies before it was over.
