  It is shown that a class of exponentially decaying time-of-arrival
probability distributions suggested by W{\l}odarz, Marchewka and Schuss, and
Jurman and Nikoli\'c, as well as a semiclassical distribution implicit in
time-of-flight momentum measurements, do not show the expected behavior for a
Gaussian wave train. This casts doubts on the physical adequacy of these
arrival-time proposals. In contrast, the quantum flux distribution (a special
case of the Bohmian arrival-time distribution) displays the expected behavior.
