To be very clear.  Your skill goes up when it is trained even if it doesn't show a pop.  Each skill has a sub-level or decimal attached to it that you cannot see.  If you train and don't see a pop, the skill went up just not over the new whole number.  This sub-level is factored, in performance, DMI, and I believe salary at the season rollover.  Training is not something that fills a progress meter and then awards a new level.
I hope that makes sense.