That is likely luck: if your order makes a nice round truck full, and that truck full makes a nice round container full at the next stage, and the container is one of the last loaded onto a ship that is due to leave soon, you'll get the best delivery time. The next order will get the worst or close to.

As some of the recent supply chain issues are easing off things will be feeling better when they are in fact moving back in the direction of what was normal.