So the pope picks Alexandria for a Crusade target. This sweet piece of territory is owned by the Shia Caliphate. I spent every dime and piety I had over 3 waves of recruited troops, mercenaries and holy orders. I could not build up enough warscore to win the crusade. I think every man in my kingdom now has Crusader and that's done wonders for opinions & inner relations of my twin kingdom of Scotland and Ireland, however the Alexandria crusade has now lasted over 75 years and aside from myself and England, not other nation has tried...and we both failed.
Tactically, taking a single province and winning the first or second battle of each of my 'waves' was easy. Heavy Knights provided by the holy orders just wreck face. The issue came after that as the Caliphate would send wave after wave of large thick stacks. I eventually resolved to reinforcement squashing and send my holy orders out into the egyptian desert defeating the reinforcements as they spawned in piecemeal. This only worked for a while as the large 15k-20k stacks of troops just kept coming. The highest my warscore reached was about 66%.
I'd also like to see a mechanic where a conquering nation can garrison/levy up a conquested holding using standing troops. Invading other cultural areas becomes a game of whack a mole. With the inability to garrison up conquested territories, the little armies that are spawned are capable of retaking the penalized holdings you've conquered. I have the troops to defeat this little armies, but I spend months chasing them around the countryside so they dont retake the holdings I conquered. I'd much rather just take those troops that I'm using to run all over the map and stick them into a castle so that holding cannot be retake with little reinforcement armies of a couple hundred men.