I strongly suspect there's an explanation other than some engineers doing one thing and others doing something else just on a whim. You'd almost have to spend a few hours by the crossing (or check with other local railfans) to find out what the issue is.
BTW what do you mean by "tired" horn honkings exactly? Is it the same long-long-short-long for a grade crossing but quieter, or some other series of honks? If the latter, the engineer might be using the horn to signal some action other than crossing the street at grade.
