Partially because you are going about it in a way that was not intended to be the way.
One thing that helps to dramatically shorten these times is to, you know, turn a character who is already good at swordfighting into an infiltrator instead of starting from the ground up. Then it's just infiltration skill you need to train.
I received a tip from Tom!? That's not something you see everyday
And I know... I even know that is a good way to start with an Adventurer to have the swordfight. However, for the entire time I used the character as a normal warrior, he won just 10% of swordfight... then, in this case was best to train at the academy. Erik used to have 90% just fighting at the battlefield, but he have years and years and and hundreds of battles.
And rogue regions are NOT intended as infiltration training areas, which is why stealing them is NOT AT ALL easier than any other regions. And potentially worse, because rogue has no judge to set you free early.
Two sides... I have a rogue region, a townsland, at my door. And I prefer to steal gold there to continue training, even being arrested, that try it with low numbers in a region with a Judge... the Judge will not release me... he will ban and deport me. Then, yes, I'm following the hard way...
I just hope to enjoy it a little before being beheaded