Different things work for different people, and if you ran faster than 1:48 as a junior it is evident to me that what you did worked for you! Some random thoughts:
*The high volume at ~13/100m pace would indeed train the muscles and nervous system in precisely the kind of form (movement pattern) that a 1:44/800m would call for. I believe that this was a major benefit of Igloi's training: volume *and* specificity. His athletes amassed *considerable* volume using movement patterns that closely mirrored how they would move in races. (NOTE that this kind of training can help to *prevent* injury during the major-race portion of the season.)
*Finding out exactly what kind of training and racing that you did during the winter ("January, February, March and April of 1974. Winter season training and cross competition.") would probably be very instructive. Note that, in Lydiard's first edition of "Run to the Top," after the distance buildup phase he switched focus almost exclusively to other work: the hills phase was six days a week, with a 20mi/32km run on Sunday for recovery(!); and then his track phase featured *many* days of track work and racing. I do not think your five days of "fast" work is necessarily excessive--obviously, your results were good!--but I'd be interested to know what went on in those winter months.
*2 x 2000m @ 5:45/4min recovery indicates some quality aerobic power--it's a session that many ~1:48 men would be hard-pressed to duplicate, especially as "just another day of training." This suggests that you were coming to the 800 from the aerobic side (rather than the speed side), and so you were probably well served by having only one day a week in which you actually hit your race pace. (Except for Monday, every day was at least a little bit slower than 54/400m pace.) A "speed" athlete might be better served by lower volume and faster pace, at least on some of the days.
*It's easy to forget that athletes who used primarily interval training achieved some outstanding results. Harbig ran 1:46.6 (a WR by 1.2secs!) and 46.0, almost 80 years ago. Coaches should always keep this kind of work available as one weapon in their armory--it is often neglected today. Among other benefits, a session like this may make it easier for a coach to analyze and correct the runner's form. Some discussion here: http://www.newintervaltraining.com/old-interval-training.php
Thanks very much for posting this!