Not entirely, I don't believe.
The most common source of adding a suit to a skill would be the Specialized Skill Talent on page 221.
Let's take a look at Lieutenant Davis, a Fated who happens to be a Guard. Lieutenant Davis has Defense 4 and the Stoic Defender Talent, which gives him the following Defensive Trigger:
Df () Glancing Blow: When suffering damage, reduce the amount of damage suffered by 1, to a minimum of 0.
That means that when he makes a Defense flip, he flips a card and adds his Defense of 4 to the total. If he flips a card, he can declare his Trigger.
It's a pretty nice trigger to have, but Lieutenant Davis decides that he would like it to trigger more often, so he takes the Specialized Skill Talent and chooses to add a to his Evade Skill. Since Defense is a Derived Aspect that uses Evade, the that Lieutenant Davis added to his Evade Skill also gets added to his Defense, which gives him a Defense of 4.
Now, when he makes a Defense flip, he flips a card and adds his Defense of 4 to the total, which means that he will always be able to declare his Glancing Blow Trigger.
If Davis later picked up a Talent that gave him a to Evade Skill Challenges, however, this would not translate over into a to his Defense (that's what the second paragraph in the callout box on page 79 is referring to).
Hopefully that helps! Let me know if you have any further questions.