It is for these reasons that it is sometimes best not to book to far in advance. Better fares can come along later even if the lowest booking class is always open. I find 2 - 3 months works best for me for leisure long haul J (cash not miles).

Loads of interesting stuff goes on behind the scenes. Revenue Management is an exciting field and well worth investing some time in understanding, not least because air travel can be blooming expensive and we can all save a good deal of cash understanding exactly how we are buying our seats in a tube.