I can certainly attest to the uncertainty factor, you never know what will get thrown at you. I recently had a regular passport appointment booked at my local post office a month prior to that for a minor and the morning of the appointment received a call that all appointments for that day were canceled since the person who processes them was out.

I don't know why nobody else could do it and they did not allow me to rebook for the following day or in the next few days over the phone and insisted I need to rebook online. Well, that entailed booking another month out. Good thing I'm not planning to travel with that minor for another few months and was planning the renewal accordingly. If I did then I'd be super frustrated, but would be making decisions accordingly if I couldn't wait another month for a regular appt.