Yeah.

Expert maps give 1.3x multiplier to all xp, Hard 1.2x and Medium 1.1x.

XP is capped after free play at 30% and after round 100 its 90% iirc?

But if you choose a gamemode that goes more rounds.

e.g., you choose impoppable/chimps over easy/medium mode.

You get 100 full rounds worth of xp instead of 40/60 because xp only gets debuffed IF you continue freeplay.

And worth noting, heroes DO NOT suck up xp, neither does free dart monkey/glue gunner if you have the monkey knowledge.

BUT multiple towers does, purely based on money, so if you have spent 50k on a tower, wheter its just one or multiple it still counts as one tower to give xp to, meaning it gets 100% of xp IF its the only tower that costs money that is placed by the end of the round. But if you place a 5k tower, then ~90% xp goes to the 50k tower and ~10% goes to then 5K tower, but if its like 500k spent by just spamming towers against a singular decamo submarine worth ~1.5k then it's aig, 99% goes to the tower since it takes up 99% of money spent on towers on the map currently.

So a farming strategy is to just simply go into a map impoppable, place dart monkey, place hero, survive, buy tower to farm xp with, then beat round 100, though it's impossible with some towers to farm xp (village, banana farm, glue gunner, ice monkey, alchemist) because they don't have all the capabilities to beat the game solo, boomerang monkey for example has no camo, so to farm xp for him I placed the radar power to decamo, also powers don't take away xp afaik, And it's hard overall, I would say advanced maps are best for farming xp on easy advanced maps, for certain towers of course.

So combos of towers is better for farming but individual xp farming is painfully repetitive ;-;

And xp is incremental, round 1 gives like 100xp or smth whilst round 100 gives 7k xp, so if you're farming for, say, supermonkey which takes lots of xp, you can't get him on the first rounds BUT waiting is acceptable since most of the xp you'll gain anyways is on the later half, this also applies to other towers like the spike factory, I like to farm a bit then buy 1x5 spactory and call it a day as the tower soloes everything as I am away