After reducing speed of firing for Photon Canons it is difficult to find Probe now: they just don't survive long enough, and the Zerg just kill them early in a game without players even seeing them.
(I suppose the cooldown is the same for the "wild" Protoss and for those that are found by player.)
(I suppose the cooldown is the same for the "wild" Protoss and for those that are found by player.)