Question - SIN to HKG to SHANGHAI to USA

Of course, it does. It is just important that your flight from Shanghai to US does not have a landing in Hong Kong of any kind. I assume it does not have, but I am telling you this just for a case. If your layover in Hong Kong is a short one or to be precise up to 6 - 8 hours and you are traveling on a single ticket, you will stay at the airport in a transit zone. In this case, you will just walk from one to the other gate and you will not be a subject of immigration and customs inspection. Also, you do not need to perform any formality and you will not fill out any forms. In the case, if your layover is longer that 8 hours, you will probably want to exit the airport. In that case, the first thing you will do upon landing is to approach 24/240 hour visa free transit where you will apply for a temporary entry permit by presenting your flight tickets. After a short check, you will be granted a permit and you will then head to the immigration. When the immigration is cleared, you can proceed to the city to spend your time on your own. Have a nice journey.