The sad thing is; Spider is not the first one to have called me that! I wonder where people get that connection...??? Digression is good. Arthur loved jokes...
I ain't 800m specialist but I can tell you this; yes, it is very important to work on the actual 800m race speed. But the question is how and when you do it. First of all, speed comes back very quickly once you start working on it. So why spend all the time honing it? You CAN do something like strides or whatever during the conditioning. More than ever, today we have luxury of doing many different things. In those olden days, Arthur's Boys didn't have much time to do much else. Whatever time was available during the aerobic phase, they spent for piling up mileage because that's what governs the performance level in 5 months time.
For repetition, it's not that relevant how fast you do those repeats as long as you do them fast enough (to creat buffer against this type of fatigue). Snell did 20X400 in 60 sec. That's not fast enought for 3:54 mile that he ran, or 1:44. But at the same time, Ron Clarke said he was doing 10X400 in 55 sec. but (at that time) he never broke 4-minute (but I'm sure he looked better than Chatterway in that ESPN movie!). So how do you add it up? It's because it doesn't matter. You're doing those repeats to stimulate your anerobic metabolism. If you have Lydiard's "Running with Lydiard", go back and read it again. There's a section that talks about how he trained Richard Tayler for 74 Commonwealth Games. That is, and Dick Brown would second, the most beautiful lesson as far as anerobic training is concerned. He also gives us another story by one Texas high school coach.
Now, comes coordination period, one of the things you need to learn is proper pacing. As jtupper agreed, it is very diffecult to hold yourself back in the first lap to run at even pace. You need to calculate how fast you can run, or you would like to run, or you think the race would be won; then run exactly at that speed, without watch (you need someone to read it for you at the end of the run); take plenty of rest like 10 or 15 minutes and repeat it like 3 or 4 times till your body learns how fast you should run. That's a pace-judgment work and it can be very important.
If you feel you need to work exactly like your race day after day, the best training program would be to race every day. In reality, you only need to put all the necessary elements developed during the program, again, in a systematic way; so on the actual race, you can put it all together. You don't need to prove to yourself day after day that you can run that speed or that far.