Recently I've been thinking the exact opposite things.
Many novice artists get too hung up on doing "exercises", because they're easy, straightforward, and comfortable (compared to doing the real thing). They waste a lot of time without improving all that much, because repeating exercises out of context can quickly become mindless, people tend to lose sight of the real purpose (making good drawings/paintings), and instead keep drawing boxes to "practice" perspective or get better at drawing straight lines.
I think what you need is a combination of what he's calling "scrimmage" and "drill".
To develop skills the fastest - try to do the thing that is as close to the specific real thing you want to do as possible. If you want to design characters - spend most of your time designing characters. You won't find a way to grow faster than by doing exactly what you want to get good at.
Then you can analyze your artwork, find the skills you're the weakest at, and deliberately practice them. But still, do it in the context of doing the real thing.
While watching an acrobat show, I came to the realization that there is probably a better way to develop skills.
These acrobats were realizing dangerous performances, where mistakes must not happen even when doing the show thousands of times. And also it must have been possible to practice it right on the first time.
My answer to that is imagination, search for the proper mindset, and switching to it.
You have to try to imagine the thinking of someone who can do things naturally.
It's kinda like in "the pretender" TV-show. It's one layer of indirection added to the more traditional "imitate the master" practicing technique.
Some tasks are best handled when you have a specific internal representation.
Often when you start from scratch, you don't have the right one, and through experience, blood and sweat, you refine it until you discover the representation that works well for the task.
But when you have a representation that kind of work but is missing something, you get stuck in plateau which practice (both "scrimmage" and "drill") only reinforce.
For example, with our acrobats, are they visualizing the actions in their head they are about to do ? Do they see themselves in 3D as a first person character, or in third player view ? Are they feeling the movements in their head ? Can they do the movements without doing them ? Can they create mental variations of the movements ? How do they handle the motion blur that our novice eye experience ? How do they evaluate the risks ?
Acrobats often are born into; and people do things without knowing exactly how they do them. So you'll have to practice observation to understand (how, why, when,...) they do what they do.
While practice is still necessary, it becomes a mere reality check for the performances you have mentally imagined doing a thousand times.
Acrobats are also doing things like practicing with a lot of padding and nets. And working up to the big dangerous stuff by doing simpler versions.
I took pole dance classes for a while, for instance, and it was only after a lot of practice that I was allowed to start doing moves where I was upside down and hanging on to the pole with my thighs. And the beginning of that involved just lifting my ass over my head (after a lot of strengthening of my abdominal muscles) and wrapping my legs around the pole, and suffering through the pain of most of my weight suddenly being on two tender little strips of flesh in my inner thighs. Once they toughened up I could start doing more interesting things.
Many novice artists get too hung up on doing "exercises", because they're easy, straightforward, and comfortable (compared to doing the real thing). They waste a lot of time without improving all that much, because repeating exercises out of context can quickly become mindless, people tend to lose sight of the real purpose (making good drawings/paintings), and instead keep drawing boxes to "practice" perspective or get better at drawing straight lines.
I think what you need is a combination of what he's calling "scrimmage" and "drill".
To develop skills the fastest - try to do the thing that is as close to the specific real thing you want to do as possible. If you want to design characters - spend most of your time designing characters. You won't find a way to grow faster than by doing exactly what you want to get good at.
Then you can analyze your artwork, find the skills you're the weakest at, and deliberately practice them. But still, do it in the context of doing the real thing.