All the above sounds reasonable and perhaps one could add to the mix and say that most airlines probably use similar business models, usually if you book early enough and get the first block of seats sold on that particular flight then you get a good price,If somebody else comes along and books on the next block of seats it cost them more - and so on until the last minute where you might get a last minute deal if they are desperate to sell the remaining seats.
I used to 'commute' weekly from Bristol up to either EDI or GLA with Easy Jet - If I booked early enough I could fly for peanuts,so I used to book as far ahead as possible (obviously),after a while I also realised that if I booked the 'wrong way round' I could change to an earlier flight on the friday without paying any extra (because ostensibly it was the 'return' leg and of course if any seats available),I rarely knew what time I was going to finish work on a friday so that was handy
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