100% agree.

There's a reason, especially in the US where infrastrutture is, erm, 'rustic', to want to wait until the check-in opens to drop bags: this is because there's next to no automatic stores where early bags are stored prior to the laterals being opened.

Translated, it means that airports like BOS, JFK, ORD and many others have "bag rooms" where the "laterals" (i.e. this place below) are used by multiple airlines during the day.



Bags that arrive from check-in, post screening, arrive at their pre-assigned lateral based on a logic established locally. For the sake of argument, let's say that BOS airport decides that BA operates out of check-in desk 7-8-9 and will use Lateral no. 3. It means that all bags for BA flights will go down to Lateral 3. However, that same Lateral might be used by another airline, say JAL, if they depart earlier than BA. If you check your bags too early, say 4 hours before, you'll still have JAL bins being built there. The JAL agents won't load your bag onto their bins, their reconciliation system won't let them, but they will put the early BA bag on the side for the BA crew to pick up after.

If there's too much confusion, and in my experience the US bag rooms are usually in that state, your bag risks being left behind. I remember ORD T5 being just like that, with row of bags almost everywhere.