Had the same thing going on in my mountain base. Filled 2+ chests full of crystals for glass (only got 3 trophies though-_-), but after some time they stopped spawning as fast probably do to spawn locations in the aria being reduced by my base. As for the spawn mechanics, I haven't gone full nerd on it as I am lazy (probably a 5 min lookup), but I do know that there isn't a cool down on golems (trolls and abominations are the same I think?) just spawn limits which is set at 1 unless in a frost cave (I had 2 at a frozen underground lake a few times...and the bats woke them both up.....F U N). It does seam that some spots are just super high on mob spawn rates as I will run into 2-4 abominations on a single coal run to the swamps but other times not see a single mob, so who knows ¯\_(ツ)_/¯.