You understood it very well. Discipline and tactics save manpower and are better in longterm campaign, but morale wins battles. That's why morale tends to be more important early game when battles are close and you focus on that one war against an ennemy with a relatively close army size and no real forts to retreat behind. It's all about winning the first battle, chasing him until you stackwipe, and carpetsieging, and morale is king. Discipline becomes vastly superior later on. Sure, you can win a battle and lose slightly more men, and start a siege of a level 8 fort. But by the time you advanced slightly he comes back with all his morale back up, and you may win it again, and once again lose more men. But then he comes back, and after 10 forts, you'll eventually run out of manpower and money if both of you have similar strengths but he chose discipline and you chose morale. And in the contect of doing a WC, you will win every battle because you outnumber everyone you fight, so what matters is that you save up your resources.
As we mentioned catch up mechanics in techs, here is a perfect example from my current game:
This Admin tech costs me less than 140 admin points. Not having it earlier sure harms me a bit (textile manufactories are wonderful in my area), but I'll only be 2-3 years late on admin 17 by doing that, and this is the one I want at all cost. If I took 11 on time, then 12 on time, and so on and so on, not only would all of my techs have been more expensive because the neighbours bonus and spy network bonus would have been smaller, but I would also have delayed my admin ideas (which I was forced to take as third group because you can't convert provinces to animist without religious first), so I would have lost points, time, and maybe manpower from revolts, from not having reduced coring cost earlier, and even more monarch points for not having civil service before teching. So yes, I would have been earlier on 11 and 12, but I don't care. What matters is that with what I did I ensured I had tech 17 as early as possible.
There is NO way I could have hit tech 17 on time without intentionally delaying unnecessary admin techs, considering I forcespawned 3 institutions in tropical climate and cored 1000 dev, including a good part before I had admin ideas. Oh and I also got stolen about 500 admin by Ming.
That's why delaying tech is actually a way not to be behind in the longterm. Once again, the difficulty is to know which tech you can sacrifice, and there clearly is a tradeoff as my economy lags behind what it should.
Edit: It seems I was overly pessimistic, I can get it
ahead of time.
To follow up with similar strats, as you notice I am intentionally falling behind in dip right now. I'm completing influence and integrating 3 vassals, which means I'll be able to max absolutism around 1630 by decreasing autonomy after the integrations. And then I'll use the same comeback mechanics to hit Dip 23 on time and overall save up thousands of monarch points (cheaper annexation because I will complete influence and will have Admin-Influence, then even cheaper annexation if I time it right because I'll use the absolutism of the first integration to finish the second,and of the second to finish the third, and cheaper tech because of neighbour bonus, spy network and more ideas, cheaper cores during the following years because I will have farmed absolutism).