For me, usually:

USPS First Class Mail - from California to Shah Alam - will take min 10 days to max 14 days. Never more than that. Anything that came out from any ulu cities, will take double the time. Usually east coast will go through main in Florida and west coast will go through main in California.

USPS Priority Mail - usually 10 days will reach, never more.

Actually can say that it's quite fast dy.

Once I bought something from China - took a damn 5 weeks to reach. WTH?