That aside, gaining the desired multiplier can be problematic at times (but then, to excel at everything IS quite a chellenge).
Everything was never the goal. The goal was two good stat gains (three if you didn't want to put a point in luck). Even this was alarmingly far from reach however. Spam just one of your class skills and you get one good stat gain and one horrible stat gain (and the single point in luck). Use your skills normal, you get two horrible stat gains (and the single point in luck).
The system itself is well thought-out, it makes sense to me that a Thief wishing to border on a Warrior's battle prowess shuld be required to do a lot of "extracurricular" activity.
A mage trying to master both their prime stats, willpower and intelligence, by casting spells will get horrible stat gains for willpower and/or intelligence. THAT is why this system is flawed.