Obviously you can check in online 24 hours before, but does the same limit apply to getting to the airport and physically dropping off luggage?

I have a relative who will arrive on a flight into LAX at noon, probably not on American, and definitely on a different ticket even if she is.
She has another flight on American out of LAX at 9pm. What she'd like to do is checkin for that, and go to the lounge. But will she be OK to drop off her luggage so she can go through security that early?

I've searched but cant see any references, nothing on the AA site or here that I can find about maximum time for dropping off luggage, all the references are to the minimum allowable time.

Apologies if the answer is "obviously you can", but for example if she was at Heathrow with BA, you absolutely cannot drop off luggage more than 3 hours ahead of time so wanted to be 100%.