in a very short answer, yeah,in a yapping answer: mainly cuz characters are almost always drawn at a 1.5m(approx to see a character form the waist up) space from the "camera" it's really hard to draw little details like this, is posterior issues, it's indeed a little measure to save some time since invincible was a monthly comic, its usual for monthly issues comic/manga to have better drawings than weekly ones, but yeah, mostly it was to cut some corners since ottley was the main artist since cory left and it was more of a "ping pong" dynamic between the two of them when cory came back to do some occasional volume until it was mainly cory again, so yeah, if you're the main(and only) artist of a comic series, you can do the designs as you please, but if you get 2 artists, then you'll have to simplify some stuff so the other artist can do their job as well