Pretty much 100% of my deaths while leveling or farming dungeons is due to those two things especially Leeway seeing mobs hit you from 40 feets away is extremely frustrating as for Spell Batching, I just love it when I vanish a mob fireball but it still hit me and I die or I drink my potion and get hit at the same time and still die.
What are you saying? There is no spell batching in “modern” wow I don’t see two mage able to sheep each other at the same time and both end up sheep and I don’t see mobs hitting me from a mile away when I run away from them.
As far as I know Spell Batching and Leeway were Artificially made up by Blizzard to simulate 2004 Vanilla WoW gameplay and server/connection lag.
You can go onto retail right now and confirm leeway exists in 30 seconds. Get a friend, have them stand against a wall while dueling you. Attack them from max range and then have them start running against the wall while you strafe back and forth and your melee range will increase.
I have no idea for PVP by what I can see its similar but I’m pretty sure its not the case for mobs, unless the test I did are completely messed up, I was able to farm for example ZF on retail with a mage without getting hit once trying to simulate what I do in classic, it was super easy not to get hit, I was able able to be kind of close to mobs without being hit a single time, doing that on classic right now would be impossible, I did like 10 tries to be sure but who knows maybe I’m just crazy.
As for spell batching something like 90 ms batching would be perfect, right now on classic spell batching is way more than 400 ms they did something to it to allow for example two mage to sheep each other at the same time, normally only one sheep should go through not both.