Fun fact: only two of our current staff members are American.
We always try to choose restock times that work for each and every timezone, but of course this isn't fully comprehensive and is by no means a perfect science. There's unfortunately no way to make restocks work for each individual member, but we do the best we can and try our best to set times that are fair for everyone, or at least make sure one of the times coincides with the less active forum times/timezones. This'll probably be the case until the users riot and replace the staff with cyborgs.
To add to this, it's worth noting that users from the Americas compromise upwards of about 70% of TBT's audience. That doesn't mean that we don't try to include the rest of the world, but using these restock times as an example, it's probably most appropriate to have both times ideal for the Americas while ensuring at least one of the two is ideal for everyone else. In other words, if you're outside of the Americas and only one of the two times works for you... that's probably about how it should be and is the fairest keeping the demographics of the forum in mind.