I understand what you are saying perfectly. I'm not personally certain this is correct (i.e. I haven't implemented the method).
I'm not personally certain it's correct, either. I guess I should have said that in the first place. I'm ~66.67% certain though. I am unable to test much because I'm already on thin ice with them. Even if I'm not correct, let's do some quick math on the two remaining approaches, lock everything vs. examine-lock.
Keeping the numbers simple, say 10 notes were released and a page hit takes 1 second. Locking all notes, even one at a time (if I'm wrong), takes 10 seconds. On the other hand, fetching details before buying will require _double_ the time in the worst case (depending on where your desired notes show up sequentially), and absolute best case it will still be one request behind the lock-everything method. As long as requests take on LC, this could be up to a couple seconds. And that's
best case, meaning being only 1 hit behind! Usually it will fall somewhere in the middle. But blindly locking everything always will win.
It's possibly correct, maybe even probably correct but I would need some time and research to know for sure. I have my doubts but it would explain a lot.
You would also need some blind luck. If you get it to work then obviously you have one answer. But if you can't get it to work, that doesn't necessarily prove anything. It just means you haven't found the proper variable names yet. On this site, just like any other, there are plenty of "undocumented features". Fortunately for us there are plenty of examples elsewhere on the site and usually you can guess how they handled things even if the target page doesn't advertise the fact. Sometimes though a little brute force is the only way and you still may not stumble upon it.