TTM attempt. A good one. Came out of the first war against France with manpower completely depleted, and stupidly decided not to consolidate. Didn't want to bother re-assembling tons of stacks. Went on to open two more wars and still do okay, then opened a third war I thought I'd do fine with, against the Papal State. I wanted to take advantage of my being at war against their main ally (Teutonic Order) to break them.
I had full stacks ready to fight them but they whittled them down and I kept on not consolidating. It got bad enough that I settled for scraps in the other war, then TO joined again. They kept winning fight after fight against my depleted, unconsolidated regiments. The warscore got as bad as 48%.
That was pretty much the most shameful moment I can remember. I remember rage-quitting my session. I was convinced I'd thrown away my best attempt ever, almost 300 years in. I'm not an elite player, I was reaching just about as far as my ability can possibly take me.
I eventually sat down, thought about it, got my resolve back, loaded the game, finally consolidated my regiments and rallied back. I was supposed to already know this, but it was lesson re-learned: Consolidate. Your. Regiments.