Worked example. Shandong cargo to USWC, Shanghai vs Qingdao
The booking. A buyer needs 1 x 40HC of fine chemical product from a factory in Zibo, Shandong, to LA. Forwarder offers two options: Shanghai 4,200 USD all-in (including 2,400 RMB inland trucking from Zibo to Shanghai port, plus 980 RMB THC, BL, seal); or Qingdao 4,000 USD all-in (1,800 RMB inland trucking, plus 850 RMB THC, BL, seal). Buyer is going to pick Qingdao because it is 200 USD cheaper. Looks fine on paper.
The failure. Buyer asks the forwarder for the sailing schedule. Shanghai has 6 sailings per week to LA; Qingdao has 2 (Wednesday and Saturday). Cargo is ready Monday. Shanghai cargo can sail Tuesday, ETA LA Day 21 from sailing, lands at LA Day 23 from cargo ready. Qingdao cargo cannot sail until Wednesday at earliest, ETA LA Day 22 from sailing, lands at LA Day 24 from cargo ready. If cargo arrives at the port Tuesday morning of a Wednesday sailing, the cargo sits in port 1 day at Qingdao versus 0 days at Shanghai. If cargo arrives Tuesday afternoon and misses the Wednesday cut-off, it sits 4 days waiting for Saturday sailing.
The fix. Buyer compares the worst case (cargo misses the Qingdao Wednesday cut-off, sits 4 days waiting Saturday): cargo lands LA Day 28, 5 days behind Shanghai. The 200 USD saving is wiped out by the 5-day delay value to the buyer customer. Buyer routes through Shanghai. The 200 USD freight premium pays back as a predictable 23-day landed schedule. Port choice is sailing schedule first, inland trucking second, THC third.