No-one ever seems to come back to these types of threads and update them with what they did and what the effect was. Now, while I'm sure there is nobody desperate to find out what happened to yet another mediocre 1:2X half marathon runner, I've came across other threads myself and always wished the OP had updated them. So I'm going to do that now.
I ran a half a few weeks ago in 1:21 and finally broke through my current 18 month plateau, finishing really well with the last 3 miles at 6:00 flat. I took the advice in this thread and simplified everything. I concentrated on 1) more miles, 70-85 rather than 60-70 2) harder marathon style long runs, so 18-19 every weekend usually taking the form of 2-5E, 10-13M, then finishing with HM level efforts and 3) MORE tempo running, but 5-10s a mile slower. The last 3 weeks on Wednesday I did 15 with 2E, 20T, 20E, 20T + cool down.
I ignored faster than HM pace work, as I felt I was OK there and really needed to concentrate on endurance. The feeling in the last few miles was great, best race I've had in a long time. Looking back, I was trying to improve my times, but doing less running. I read Wejos article and tried to change my mind set a bit, and just get back to enjoying running and not stressing about doing tempos to the exact second, but getting in to a rhythm and relaxing. Definitely think it helped, most miles I've ever done in a 2 month period but also the most enjoyable.
Looking forward to more base over the winter, getting consistent at 80MPW, and hopefully breaking sub 1:20 next year.