Oro-o the 1st and 2nd searches were thorough searches based on the baysain principle and the data they were given, the second one had one major change in as much as they were told the fail rate of beacons and that is what shifted the search ara, plus ruling out where they knew it wasn't, it was a scientific/mathematical based search not a thorough search of a huge area.
if i recall on the second search they hit it very quickly, MAH 370 would have to be a huge area as they are not even certain until debris is found, but I agree they should start based on Inmarsats best data for LKP.
Who knows they might get lucky before the debris searchers do.