I think it is a big waste of effort trying to calculate the algorithms that inventory management use - once upon a time (maybe) they were relatively simple, but now that are complex and unpredictable.

As truthknown said, though, the inventory on one flight can quite easily be affected by other flights that day (if they know one might get cancelled, for example). I think this is especially true in the JV markets with numerous flights (e.g. LHR-JFK and LHR-LAX) where Ba might cancel a flight and AA seems to reduce inventory accordingly - it can't assign seats to those passengers until BA moves them over to its flight, but it can make sure there will be some room.

For example, LHR-LAX tomorrow was showing J7 I7 W7 P7 last evening. This morning at 6am it was the same but also with C3. I called and nudged them to process my SWU. As far as I can tell I was the only seat change that occurred between 6am and 7am. Now that same flight is showing J4 I2 C0 W0 P0. Something is up, as I'm sure they didn't sell all those tickets, but it is pointless to try and guess what it may be.