If any interval, or rhythm, in your rendering, becomes too repetitious or systematic, it feels lifeless and unnatural. This remains a typical problem that afflicts beginners, but it happens to me all the time. In art, the principle of line rhythm is essential in creating a hierarchy of information that feels comfortable and natural for your viewer to interpret. Without variety, your rendering can become wallpaper fading into the background of our attention. Like an endless row of fence post, we cease to notice or pay attention.

Too much variation is incredibly disruptive, Each decision you make when putting information into your model has visual implications. Not enough unity and you have confusion. Too much unity and you are bored.