I'm not going to disagree with you. W each need to listen to our bodies ..But..(yeah there's always a but). Let me tell you what I think. When I started tri's 5 years ago I had been riding a bicycle for about 5-6 years. Spent 2 years on a comfort bike then got a rode bike. Best I could do was about 17mph for an hour. I worked at it and got up to 20mph with the roadies. Got talked into a tri and had a blast. I could barely swim. Spent the next 2 years working on swimming. Went form not being able to swim a 100 in less than 2:30 to 1:30 and I can hold 1:42 per 100 for the 70.3 swim. This is not fast but the time needed to improve beyond that speed is astronomical compared to Bike & run for incremental improvements.

In all my training my biggest obstacles are size & recovery. At 6'3" & 215 I am allergic to hills and I really did not enjoy running. I would go out and run my 3 or 6 miles as fast as I could, be sore, fell like crap and continue to hate running. By last year I was a good biker averaging 20.7 for the bike leg at 70.3 (good for top 5 in AG). Already discussed swimming speed (generally top 20%). How the heck do I pick up 20 minutes in a race to go from 10th in age group to potential podium at a large 70.3 with 60+ competitors in my AG (run around 50-60% in AG). I was giving everything back that I gained swimming & biking on the run. Because of my poor performance doing shorter quicker runs I decided to do the opposite. First thing I noticed was that running was not as "hard" and I wasn't sore the next day. It did not impact my ability to perform my other disciplines training. I slowly ramped up the mileage and had to keep reminding myself to GO SLOW. Did a standalone 10K in month 4 and ran a 49 which was quite a bit better than anything I had done previously. Felt the training was validated and kept doing it. Did a 5k a month later and posted a 22:39 - over 2:30 minutes faster than the time I posted just 5 months prior.

Fast forward to the 70.3 and I dropped 17 minutes off my previous best 70.3 time. The best part is at no time did I have any real pains, injuries or whatever. If I don't think I feel like running I still go and run at least a mile and then decide if I really want to bag the run. Usually I end up doing the run. Consistent LSD has been very easy on my body. If you had ever suggested that I would run a 15 mile training run I would have laughed in your face. I can't think of any other easy to do training that could yield this type of result. I can see that with riding 6 times a week that you may have limited extra available time. I will suggest that you could probably maintain that level of biking performance on 3-4 rides a week. If you can try this starting in the off season say October and do it through March I am willing to bet that your overall times will be better than this year and you will have an easier time handling your overall training stress. Would be an interesting experiment wouldn't it.

I know that I was apprehensive about trying this. I thought that I might break down due to the impact of running. By doing true LSD I avoided all of the issues that you alluded to in your post. I have talked a couple of other people into trying this approach. The ones that actually do LSD are posting good results. Most people don't have the discipline to run this slow. They don't trust the approach and end up sabotaging it by running too quickly