I guess what got me thinking about it is because physical oil/gas traders have demurrage clauses in the contracts which kick in when a tanker is unable to offlo

I guess what got me thinking about it is because physical oil/gas traders have demurrage clauses in the contracts which kick in when a tanker is unable to offload its cargo by a certain time. This translates port congestion directly into hard cash that has to change hands, so for this specific problem that class of traders do very much care about the efficiency of the shipping patterns.