For MEB, always.
First as to lessons, NATO remains the single most important security actor in the world, whatever squabbles periodically occur in the Alliance.
Maybe people who are younger don't value NATO as much, because they don't remember dealing with the Soviet Union, but Putin is a reminder that NATO remains central to American security, if only as a hedge against Russian nationalism becoming more assertive than we would like, even as we have to coexist with the Russians for the same reason as during the Cold War; nuclear weapons.
Thus, after Turkey had its plane shotdown by Syria, NATO rightly reaffirmed its military commitment to Turkey, implicitly with respect to the Russian Federation.
Turkey as an ally is intriniscally important as a bridge to the Middle East, if a state that has its own interests too, which of course with Greece and Cyprus makes for some difficult Alliance management at times; if the Alliance were to ever wither or dissolve, the Russian Federation would be the only clear winner in terms of increased power, something Putin understands very well having been posted to the GDR.
Second as to lessons, Alliances repesent the interests of their members, who are sovereign states.
This is why to date, NATO's response was more muted than some might have liked to the shootdown, although Syria also climbed down a good bit from earlier bellicose statements precisely because the awesome military capabilitites of NATO started to be engaged at least implicitly the second they took a shot at the Turkish plane, because under Article 5 of the Treaty, invoked only once on 9/11, an attack on one member is an attack on all, calling therefore in theory on the potential use of American tactical and strategic nuclear weapons en extremis. (As to why that is the case, the alternative would be a nuclear armed Germany, plus probably Italy, Spain, Turkey, maybe Greece, etc...)
The reason NATO was somewhat muted in its response to the shootdown is that in fact, there was some ambiguity as to what the Turkish plane was doing when it was shotdown, as to engaging NATO military action, yet.
As to why, it would seem that the plane was doing something we do too, just in case, which was collecting what is known as ELINT, short for Electronic Intelligence.
As to why one collects ELINT, and the third lesson, to take down an air defense system, necessary in any state's intervention in Syria, to preserve your own planes, you want to know what frequencies the enemy's air defenses use to lock on for missile fire.
Once you have their frequencies, you can send things right back dow that path, and we have gotten very, very good at doing that, which is why we don't lose planes in wars very much anymore, although enemies adapt too.
As to the F-4 episode, there is therefore a game of chicken between planes seeking to draw out a signal from the air defenders, in order to register that system's frequency, should you want to blow it up later, although that means that system "paints" you, and can therefore blow you out of the sky, possibly, depending on various countermeasures once a missile comes at the pilot-bait.
That's the third and more subtle lesson of the Syrian affair, which is if the Syrians are brutal, they're not dumb either, since apparently they didn't paint the plane much if at all.
Of course watching us operate against Iraq helped as to our strategies and tactics, and Iran would know this too.
What happened in the Syrian affair is something the Russians always advocated, if to their frustation only the North Vietnamese got the point, which is the "wall of steel" tactic in response to the response to the opponent's air defense system.
In this case, the Syrians didn't take the bait as to fire control radars being turned on, at least not apparently for long, but, they did lay down a barrage of anti-aircraft artillery, triple A, that mashed the Turkish plane very quickly, because they put up a wall of steel in front of the plane's trajectory estimated presumably from non-fire control radars and general tracking information that didn't give away their own position.
That last lesson is that enemies adapt to your counter-measures to their defensive measures, and can't be relied on to be stupid, something that would be important to make sure with Iran in any strike, as to some sites probably being defended having learned some lessons from Saddam's failures against Western air forces, if that action-reaction cycle of course is always present in war, at least for those states that practice it very long.