while i would agree that larger changes do infact provide better dilution of things in the water in your tank, think about this, your in a hot tub, then all of a sudden, someone walks by and drops in a single 10 pound bag of ice, you might feel a cool spot for a few min, but little if anything, now, lets say replace half of the hot tubs total volume with ice, now your gonna jump up.
Your fish dont have the option to leave the hot tub to get away from the change.
Personally, i wouldnt do more than 20% per week,(in a single shot) unless you have a really good reason, or say 5-10% every 3rd or 4th day...
the main idea here is to change things more slowly so as to not stress anyone out.
The other thing to think about is just how close the "new" water is when compared to the "old" water, if its exactly the same SG, and exactly the same temp, then i would say that you can go with higher % changes, cause it will cause less stress.
Just my thoughts, YMMV