As I said elsewhere there is another thing to keep in mind: soft cap and hard cap. Hard cap would be when Buzzer-manager shows a player as 100% capped (give or take, CP is more accurate). When it shows something like 93%-100% it means the player might have reach the soft cap and training will still progress, just not at full speed.
Example: Allstar potential
An Allstar potential can have anywhere between 6.00 and 6.99 Potential. The maximum you can train the player is 6.99 after that it's widely assumed the speed drops to 0, but between the actual value and the maximum value you can still train at a reduced rate.
Say the value of the actual Potential is 6.5. 1->6.5 full speed. 6.5->6.99 reduced speed. 7.0+ no more training.
Obviously between 6.5-6.99 the DMI will likely still go up if you train a primary skill.