There is nothing wrong with experimentation, so have fun with it.
I don't think the physiology discussion will be all that surprising to you. And forgive me from starting at the beginning, because it is clear that you understand most of this stuff, but it might be helpful for others to hear it, and the easiest way for me to describe it is to start at the beginning.
The idea is that there are several factors that limit distance running performance, the most important of which are your body's (1) ability to get oxygen to the muscles that are engage in work, (2) ability to use that oxygen efficiently once delivered, and (3) the ability to clear the waste products from your muscles once they start producing energy without primarily relying on oxygen. There are more factors to be considered, but Daniels and many others emphasize these limiting factors (let the cavalcade of Daniels detractors commence!).
The goal of a well integrated approach to training would attempt to address each of these limiting factors by introducing a stimulus that will cause adaptations that will reduce the impact of those limiting factors. Most would say that you address (1) by way of vo2max workouts, you address (2) by way of running economy workouts, and you address (3) by lactate threshold/tempo workouts. Again, this is a place where detractors will jump in and say that there is no good scientific evidence that working out at paces that simulate vo2max pace or threshold pace improves your vo2max or your LT adaptation. I haven't done a survey of the published studies, so I cannot address that, but I can say that these kinds of workouts have paid large dividends for a couple of generations and anecdotally, they have worked for me.
I will say that I periodize my training plans and don't emphasize all three kinds of workouts in the same week. In fact, I often ignore running economy workouts for extended stretches (assuming that you don't count strides or running hard up an occasional hill as running economy work, which you arguably could). So the question that I think you are asking is, can't you just work your LT adaptation in one phase, then emphasize your vo2max in the next? While I have seen plenty of discussion about how long it takes to effectuate vo2max adaptations (4-6 weeks for improvement, then limited improvement after that, then a loss of vo2max adaptation within a month or so after that) I cannot really tell you how long it takes for LT adaptations to subside over time. The conventional wisdom has always been to work it in consistently, in part, I believe, because it is a relatively low stress way to get in a second workout in a micro-cycle.
Another logical question would be: won't some of that adaptation be maintained by the vo2max workouts? I think the answer to that is no because, by the nature of vo2max workouts - relatively short bouts of work with moderately long periods of active recovery - lactic acid is cleared before it can build in adequate amounts to effectuate adaptation.
If anyone else out there has any good information about how long LT adaptations can be maintained without LT workouts, I think that would be interesting to hear about.