Update
Okay, so I began the 3 times every 2 week regimen a little over a month ago, together with the marginal post-failure work as I had described in my earlier post, and ran into a bit of trouble. Whereas I would normally work out on a Monday and Friday of one week and then the Wednesday of the following week, it turned out that I was not able to do a workout on a recent Friday as scheduled, and so I did one a day earlier on the Thursday. This was with the post-failure work. I could not sleep well at all for the next 2 nights, and I could attribute it to nothing other than the all-out workouts spaced closely together. (I should point out that when I was going simply to full concentric failure and not beyond, I would normally work out twice a week, on Mondays and Thursdays.)
I realized that even at 3 times every 2 weeks, I was spacing the workouts very close in the recovery cycle for this level of intensity. Truth be told, I really do like the level of intensity that is just a bit past concentric failure as I had described in my earlier post. It really feels like I did something. And so, although I wrote earlier that if things did not go as expected that I would reduce the intensity and up the frequency, in fact, I will do the opposite. I will be keeping this level of intensity and reducing the frequency to only once a week for resistance training. I will continue to do 2 HIIT workouts each week, one right after the RT and one on the weekend a few days later.
Inspired by other independent research and what Doug McGuff wrote in his book and said in his various talks, I decided that I didn't want to spend all of my time in recovery and virtually none of it above baseline, where actual overcompensation and adaptation normally occurs. I tried this 1x/wk frequency about a year ago but switched back to a higher frequency after a couple of months. I did not notice a change in strength or body composition during that time, but just felt a bit antsy to get back to the gym more often. However, I wasn't going past failure then, so it wasn't quite the same. Who knows, maybe this time the results will be a little different.