There are VO2 max sessions & LT runs in the P & D schedule I just need to find where I have put my copy again. I agree with Moraghan to a certain point in that you can't just parachute a 10 x 800 into a schedule it has to be built up to and indeed perhaps passed. But at the same time we don't want to make this too complicated, the whole thing you need to be getting used to is running at and indeed faster than your race paces.
I doubt if many runners actually understand the terms VO2 and LT fully, I wouldn't begin to think that I do its simply not in my areas of expertise (however if you want to know about ships I'm pretty good) though I get the idea. Speed work does many things but in my opinion the benefits which are oftern overlooked are that it gives the runner confidence that they are able to run at paces far faster than their general aerobic pace, and that it teaches the runner to know what different paces feel like and hit them without reference. Running at race pace for extended periods can be further developed by tempo runs or as I prefer by running lots of shorter races though not necessarily flat out. Marathon training is not rocket science, LSR, Tempo, Intervals Medium LR, two recoveries, rest day pretty well covers any schedule, the variances are how you do those tempo / speed sessions.
IMO too many people get hung up on the technocalities of the sport, if you want to run fast you have to train fast some of the time. How you do that could be the subject of many a book but as long as there is progression in so far as you do more reps or do them faster or reduce the recovery period you are progressing rather than stagnating.
In short there are many ways to crack a nut.
