5 tiles = ~1 gold =>
25 tiles = ~5 gold =>
50 tiles = ~12 gold =>
70 tiles = ~19 gold =>
88 tiles = ~24 gold =>
113 tiles = ~42 gold =>
153 tiles = ~69 gold =>
173 tiles = ~86 gold =>
185 tiles = ~100 gold =>
201 tiles = ~115 gold =>
210 tiles = ~122 gold =>
Carts apparantly carry fractions, which add up at the market after being dropped.
210 tiles 15 carts for 5mins=>
5 tiles 15 carts for 6mins=>
5 tiles 10 carts for 2mins=>
5 tiles 5 carts for 2mins=>
25 tiles 15 carts for 6mins=>
25 tiles 10 carts for 6mins=>
25 tiles 5 carts for 6mins=>
50 tiles 15 carts for 6mins=>
50 tiles 10 carts for 6mins=>
50 tiles 5 carts for 6mins=>
70 tiles 15 carts for 6mins=>
70 tiles 10 carts for 6mins=>
70 tiles 5 carts for 6mins=>
210 tiles 15 carts for 8mins=>
210 tiles 10 carts for 8mins=>
210 tiles 5 carts for 8mins=>
Conclusion: Trade cart efficiency is more dependent on length of haul, than on cart congestion, for longer distances. There is an increase in gold per unit distance with increasing distance. For all practical purposes, you cannot make too many carts with respect to cart congestion for long hauls. All tests were performed with trade carts, but I suspect an increase in efficiency proportional to the speed increase with the caravan upgrade.