I can say that one of the reasons that I bought Jeanne and Scott's books dead-tree style is because there are so many distractions when reading on an online device.
Can some people focus and self-discipline enough to ignore the million notifications constantly coming in not directly relating to what they are trying to learn? Yes.
Do many people find it easier to say "I am just reading these 15 pages right here I just flipped thru with my fingers, and until I am done reading them nothing but reading, reflecting and taking notes and looking at the notes (which I would also do on paper)?" Yes.
I often go down rabbit holes when I am reading/watching materials online. Most of the time, the stuff I am looking at is either good review or something I will need later.
But it often is NOT directly relevant to getting the details in hand properly understood/memorized.
One of the things you referred to in one of your other posts is the absolutely insane time pressures on the 819.
If you know everything, but have to think about it for a good long while, you can be toast even with best test-taking practices due to lag.
I really feel you need to know things as well as the name of the street you live on, your dog's name, favorite actress.
I have had almost no trouble comprehending any of the material, I understand almost everything.
But being able to go thru the
test means being able to pretty much instantly recall a very wide body of information, often no longer neatly compartmentalized the way the chapters are originally presented. One problem has you recalling and integrating things from Chapters 5 and 11 of 816, but if you noticed the one trick from the 3rd chapter of the 815 book you can answer instantly without even thinking about those....
Caveat -- I haven't taken the 819 yet, however, comparing my performance and times on mock stuff with those who have has resulted in me wanting to know everything backwards-and-forwards, "cold".
I already thought of myself as a good/fast test taker from SAT's, GRE, standardized tests and 5 years of engineering school...I feel like the 819 intentionally is hard and demands you know everything in a way that you can quickly spot details, recall near-instantly, etc.
There is a spinoff to Jeopardy called "The Chase" where the contestants are competing against 3 top Jeopardy champions...the harder parts feel like that, in that the people who win almost always answer the questions before they even finish asking them.
We see some people here that have breezed thru and aced it, some of them may just be fantastic at
Java due to deep experience, but knowing the material "very well" and maintaining a focus that leads to high velocity thru the test (including recognizing questions
you should just take a wild-ass guess at and move on because you can probably do 3 or 4 others in the time it will take to complete them) also seems to be something they "just do".
p.s. My dog is my study partner. After I have gone thru enough material, I go for a long walk with him and tell him all about it while we walk around the neighborhood sniffing things and peeing on them. Well, we divide the work up asymetrically....
Good Luck!