The consensus at this point is that there is no consensus. The sustained push seems to be the more common view still, but criticism of it is becoming more frequent. One of the big issues seems to be one of terminology, understanding what othismos really meant. It could literally refer to pushing an opposing line with bodyweight, or it could more poetically refer to the general force of a battle and strength of arms. We just don't know, and Thucydides and Xenophon refer to situations which could fit either interpretation.

I will say however that if the "decisive heavy push" theory were true, battles like Delium, Mantinea and Leuctra where one unit has a significant depth advantage should have ended a lot quicker than the two authors make it seem. Leuctra in particular - the muscular advantage of a 50 deep phalanx over a 12 deep one is overpowering; yet Xenophon tells us the thinner managed to stand their ground long enough to extricate the wounded Cleombrotus:

Still strong evidence exists for supposing that Cleombrotus and his division were, in the first instance, victorious in the battle, if we consider the fact that they could never have picked him up and brought him back alive unless his vanguard had been masters of the situation for the moment.