I have not been tracking lately but I was a couple of months ago on the SFO-TYO route. A brief look leads me to believe not much has changed with award release since then. I suspect there is just a large demand and AS is last on the totem pole to access these awards so folks with access to other programs that can book further out than AS are taking the awards. Note, this includes AA who has a few hour advantage over AS in booking at the window.

SFO-TYO, last I checked was making around 6J available most days (except Fridays and Sundays where only 2J were released) a couple of weeks beyond the AS window and those seats get eaten away slowly up until the AA and AS windows open at which point they go faster. it was rare for J to last a week beyond the AS window opening but in non-peak season there were usually a few dates that would last into the AS window. At peak season I can imagine it will be even harder. Some folks may grab what they can at window open and change to a day or two later so keep checking frequently because some seats that are taken now may be returned to inventory when someone cancels.

If you want those awards at peak time at window open you want to try as soon as they become available. Don't sleep in until 8AM and expect to snag them at window open (unless maybe you are on the East Coast).

Use another program to check availability coming up just outside the window to determine whether you have a chance at window open or not (if there are no seats available today for a date that AS opens tomorrow then come tomorrow they probably are not going to be available either. Right now I see SFO-HND has 6J available (checking on BA) for 12/18/23. Today 1/19 AS can book through 12/16/23 so in two more days 12/18 will become available if no one takes them. If you want to have a chance at those you will need to be booking early in the morning and use the reverse round-trip trick, otherwise -- No Soup For You