Not sure if its a minor idea -
Anyways, what happens in real life is that you interview for a job, and based on your qualifications (labor points?) its decided whether you get the job or not. However, once you are already assigned and working, whether or not you get a pay-rise depends on performance and experience with the two being inter-related. An experienced but less educated banker would know more about banking than a fresh finance graduate.
Point - of course, the labor point system continues to exist but you have a counter of how many hours a particular job has been completed, and based on total hours you have some kind of experience bar - the more hours you put in towards a job the more the rewards - this means that someone who has been doing robbing trains at least two hours every day for 2 months should be getting X times the reward (money, luck, xp, item drop percentage) than someone who does it very occassionally.
The rate of return should have a step-curve - this means that after, say, 20 hours, the marginal returns should be diminishing and should remain stagnant for quite a while till you get a threshold point after which the additional returns jump again - and with more and more hours you put in the stagnation stage gets longer and jump gets less higher - there is an extent to which one can perform at a job, and after a certain point no amount of experience helps because you are already at the ceiling level performance.
If its still confusing - say, I and playerX both have 10 lp to train robbing - I have been doing it every day for at least an hour, and playerX doesn't do train robbing regularly, then I should be getting 10% more money and experience points, and a substantially higher probability of finding a fat bag of loot than playerX.
Just a thought....