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.