I've added pages to my present passport seven times using US Embassys in Asia, and it usually takes just a minute or so. Lately, the BKK embassy has been wanting to give me a new pp, as my current one is thicker than a bible. They say that some countries such as China may not accept the pp in this state (total BS), but I refuse to let them issue a new one as it will kill most of my active business visas (which they say will not happen - more ignorant Embassy advice). Thus far, they keep reluctantly adding more page inserts.