Considering you don't give any basis... it's terribly hard to believe what you're saying as anything other than some regurgitation of something you've read in the past, without any understanding of it. Think about it, what good does it do a criterium racer having 5+ hour endurance? Not much. Base miles have to be a huge majority of your time on the bike if you're only got 5-12 hours a week to train a week. Spending 60-80% of that going long and slow doesn't benefit you much at all. Worry about your TSS score (if you're going to bother calculating it) and/or fatigue levels. All your training you want to thoroughly stress yourself without over training. With tons and tons of base miles on a 5-12 hour/wk workload you're not taking on much stress at all and not going to see much gains. Now, with the OP, who's got 20+ hours a week, base miles are essential to prevent over training. Again, we're talking CRITERIUMS here, which tend to be less than 20 miles if not half of that. The person having a FTP of 350 but doesn't have the kick after 3+ hours is going to beat the pants off the guy who's got an FTP of 275 but can call on that power after 4 hours in the saddle.

And since people seem to like videos...

Or read "Time Crunched Cyclist" by Chris Carmichael or any of the forum discussion regarding it, or any of the lab testing that's been done. Base miles are a waste of time on condensed schedules, train for the event that you're targeting. Your idea is like telling a 5k runner to go walk marathons in Z1 to train, it doesn't make sense at all as you're getting very little return for the precious hours available.