if you have 100's of acres of prime hunting land, I think even signs and laws will not keep trespassers out.
That is where the
state resources and enforcement of laws piece comes into play. No question protecting larger tracts is an ongoing effort anywhere.
In some states (particularly in the southeast), though, DNR is so understaffed that they either can't respond to the calls, or when they do and they catch people baiting and hunting without permission, it could be a slap on the wrist and they are back at it next week in a different spot or on someone elses property, whereas in other states they will take your conveyance, firearm, and put you in the clink for awhile.
I think tough laws are a deterrent to some extent.
To the broader audience, keep in mind this was posted in the whitetails section. My goal is to manage for trophy whitetails (4.5 yrs and up), which requires protecting my property from unauthorized hunting as well as confidence that the state will protect my rights from those who do and punish them when they are caught.