I think for the most part The USPS do's a pretty good job,but they are a mystery to me.
I shippped a 30 lb clock to a guy in Alaska a few yrs back,he wanted it snail mail,they said 3 weeks via truck,he got it the next day.
I shipped Some very rare Vac.tubes to a guy in L.A (about 400miles) He wanted Overnight express (cost 50 bux).
Took 3 weeks