Not quite decades, but yes, for a good number of years now.
That was
Christopher's question you answered, not mine.

But thanks!
Ach, yes of course. So sorry!
^^I note that when I see comic-book scripts and compare them to the finished pages, the dialogue has often been trimmed down or rearranged in the latter. I suppose that's to get them to fit the balloons/art better.
Christopher--
Yes, that's frequently what it is. Sometimes, though, it's some other logistical or design problem... for example, the artist might have inadvertently drawn the characters with a placement in which the dialog flow didn't work correctly, was out of order, etc. (which, in truth, could have also been the writer's fault, by not realizing that he had already blocked out the characters for the scene in a way that would later cause dialog/ballooning problems).
Sometimes it's that the ballooning would have looked awkward, such as tails going through characters' faces, or across important action, or even criss-crossing each other--which *really* always looks distracting. And, sometimes, it's even just because the artist really kicked ass on a scene, with his facial expressions, posture, pacing, etc., and some of the dialog simply ended up not being necessary.
For example, this happened in New Frontier #1, when artist Stephen Thompson drew Calhoun rolling his eyes in such a way that an entire exchange of dialog was no longer needed, and would have even distracted from the timing of the scene. (And, when you find yourself actually
eliminating Peter David dialog, you
know that the artist really did the trick.)
So, as you can see, the whole lettering trade is really both a science and an art, even with it being so heavily computerized now.
Byrne, meanwhile, actually helps out his IDW editor immensely by doing his own ballooning guides--as both the writer and artist on the book, he can take most of these adjustments into account ahead of time, and that makes deadline production on his issues all that much easier.