How does this military service to create good citizens factor into this newer understanding of Greek warfare?

It doesn't, because only a small minority of citizens went through the ephebeia until the very end of the Classical period.

Now, I'm saying this with confidence because it's what I believe on the basis of the evidence we have, but this is actually a long-standing controversy. Did the existence of the ephebeia make the Athenian hoplite into less of an amateur levy and more of a trained reservist? The basic facts are these. Our best source for the ephebeia is the Constitution of the Athenians written by one of Aristotle's students in the 330s BC. This text describes the ephebeia as a mandatory two-year military service for all male citizens who turn 18. It also lays out exactly what they did during their service:

Some of them garrison Mounichia, others the Point. And the people also elect two athletic trainers and instructors for them, to teach them to fight in armour, and the use of the bow, the javelin and the catapult. (...) They go on with this mode of life for the first year; in the following year an assembly is held in the theatre, and the cadets give a display of drill before the people, and receive a shield and spear from the state; and they then serve on patrols in the country and are quartered at the guard-posts.

-- [Arist.] Ath.Pol. 42.3-4

If this weren't straightforward enough, we also have a large body of inscriptions from the same period, on which different demes of Attika listed the ephebes recruited to the programme that year, and honoured their officers (who are recognisable by their unique title). It seems at first glance that this was a well-established system in Classical Athens.

However.

All known inscriptions related to the ephebeia in this form - without exception - date to the period of 335-322 BC. This period, between the reforms of Lykourgos (the Athenian one, not the Spartan one) and the defeat of Athens in the Lamian War, is also the period in which the Constitution of the Athenians was written. There is no earlier reference to the system's officers or to the content of the training programme.

In fact, the only references to the ephebeia that show this programme existing before 335 BC suggest that they're referring to a very different programme. Sure, Aischines claims that he was out patrolling with the ephebeia sometime in the 370s BC, and Xenophon says the ephebes trained in the gymnasia and processed with torches at religious festivals in the 350s BC. But Xenophon specifically brings this up in order to propose that they be paid to do so, because otherwise they can't devote themselves to their training and public duties. Apparently as late as 355 BC, they weren't being paid a wage to serve. But according to the Constitution of the Athenians, they did receive a wage:

The people grant the disciplinary officers one drachma a head for rations, and the cadets four obols a head; and each disciplinary officer takes the pay of those of his own tribe and buys provisions for all in common (for they mess together by tribes), and looks after everything else.

-- [Arist.] Ath.Pol. 42.3

This is the crucial difference between the ephebeia before 335 BC and the one after that date. Without compensation, most citizens would not have been able to afford to send sons in their prime away to prance about the countryside for two years. As Xenophon notes, even the people who volunteered for the programme weren't able to attend because their labour was needed elsewhere. The necessary counterpart to making the system mandatory (as the Constitution of the Athenians says) was to offer a wage to the ephebes; otherwise it simply could not be done. Add to this the reference to training in the use of artillery, which was unknown in mainland Greece until about 370 BC, and we can be sure that we're dealing with a wholly reformed institution of the very end of the Classical period, not a traditional education programme of immemorial antiquity.

The older ephebeia that Aischines and Xenophon refer to must have been a much more modest programme. We know nothing about its content except that it involved athletic training and some patrolling of the countryside and the walls. We don't know when it was introduced; some scholars believe it dates back to the Archaic period, but our concrete evidence allows us to trace it no further back than the Peloponnesian War (by inference) or even the mid-4th century BC (by explicit mention). We know nothing about how long the ephebes served. Finally, we must assume that only the richest citizens could afford to become ephebes. The effect it would have had on the citizen body as a whole would have been slight; the incorporation of the minority of trained ex-ephebes into larger bodies like the cavalry and the phalanx would have diluted what skills they had to the point of meaninglessness.

In short, this older ephebeia seems to have been much more about sons from rich families proving their commitment to the city in order to start themselves on the ladder to political prominence than it was about drill and discipline. The rest of the hoplites and cavalry, our sources explicitly tell us, received no military training at all:

The state does not publicly train for war.

-- Xenophon, Memorabilia 3.12.5

In that sense, the reformed ephebeia of the 330s BC addressed a real problem - but by that point it was already too late.