It has been my experience that pressure can send them in the thick without a doubt.
I remember about 20 years ago watching a guy work a bird HARD and hearing him gobble prob 75 times, but he wasn't coming out of the thicket he was in no matter how "Box call Willie" worked that boxcall. The next day I heard him gobble a few times and eased in listeing for "box call Willie" and sure enough, he wasn't there calling. So, I went into the thick about 50 yards and yelped twice and waited after he gobbled once. He came in snaking his way through the many vines and downed brush. 1 1/4" on this one.
Can't wait for April!
Wess