The US is a huge continent, so it would really depend on where in the US you are going.
I bought paintball gear from the us, and it took about 5 days to clear
About 6 hours.
45 minutes.
About 6 hours.
About 19 hours.
about 11 hours.
About 16 hours.
6 hours
About 11 hours.
It is approximately 21 hours and 48 minutes long
Johannesburg to Tokyo via Hong Kong or Singapore is close to 18 hours
It will take about 11 hours and 10 minutes.