As I said in
this thread, they doubled the base skillup rate for parrying. They likely also increased it for Guard and Shield.
The problem with skilling these abilities (especially Guard) is that you have to fail evasion, counter, etc. checks before they even have a chance to proc, and then the proc rate is incredibly low (~5-10%) on anything that you can get a skillup from. Then, on top of that, your odds of skilling up per Guard/Parry are also pretty low (it used to be ~2%). So any time a monk with a 50% Counter rate and a 20% Evade rate takes a swing, they only really have a 0.04% chance of a skillup. At an average of .2 skill per skillup, they would need to take about 5 million swings before they'd cap guard.
Lower your Counter rate. Floor your evasion rate. Now you only need to take ~2.5 million swings to cap guard.
After the patch (doubled skillup rate), you'd be looking at about 2 and 1 million swings respectively. It's not impossible to take a few million swings, especially with a hoard of Mandragora/Phalanx and afking. It's freaking dumb to have to do that to cap skills though.
They should eliminate skilling up. Skills should just auto-cap when you ding the next level. Skilling up is an annoyance at this point that doesn't add actual interesting content (anyone can afk in Abyssea with Regen Atma). I wish they had opted to eliminate it instead of investing so much effort in items/foods that increase rates.