This is a very interesting question and I’m not sure I can answer it but I’ll give you what I know.
If you have read this article you know Lydiard mentions needing 7 months for a complete program:
My original training schedule requires seven months to complete. It starts with a three-month long aerobic build-up, followed by a month of hill resistance. Then you move on to a three-month long track training. So if you are a serious marathon runner and the race is in October, you should start your marathon conditioning build-up in March.
However, as you mentioned, he states elsewhere (I believe one place is within this article) that you can/should continue base training as long as you can afford. Now, I’m not sure he was thinking anyone would say they have a relatively unlimited time. I’m suspecting he was thinking of someone saying their goal race is 10 months off. In that case, he’s saying take 6 months for base training and then roll into the hills and continue on.
Now, an interesting note about this is the response I got about 2.5 years ago when I was thinking of just what you are thinking about that Lydiard said. I went to a couple of forums and asked what people thought if I base trained through the spring and only had one racing season for the year, in the fall. Some people said go for it, quoting the exact passage from Lydiard I was thinking of. Some others said that I shouldn’t artificially extend the base phase, only do so if that’s how a racing season works out. They argued that sticking myself in base building for so long would leave me hurting when I tried to add speed back in and I would be hurting my overall development.
Now, I am doing this year precisely what I was thinking of doing when I asked that question but the situation is different than it was then. After a couple of years struggling, I started this year from scratch so I took the spring to build some baseline fitness, basically what you are doing right now, before going into a training plan for the fall. The results this fall will give us the final word on how this worked but, right now, I feel like things are going very well.
What’s the moral of the story? I’m not sure, maybe I’m just rambling. I think if I were in your situation, I’d probably pick a goal race in the spring and build a training plan around that. Given your situation, that would be similar to what I’m doing this year. It gives you time to build a baseline fitness, then get into quality base training and transition into race preparation phases. You can then go back to another approximately 7 month phase after that to incrementally build your fitness from one season to the next.