When we play the US sends 50% of their income every single turn (to people in the war). It’s usually 20/10/10/10 Russia/Uk/India/Anzac unless someone is in trouble. That means 4 separate rolls every turn to spread the risk. We never send more than 20 due to interception. We always send Russia 20 every turn and Anzac gets the least amount. Most of the money ends up making it into allied hands. Every third turn or so the Axis end up intercepting. Sometimes they intercept 20 IPC from Russia, but sometimes they only intercept 6 ipc from Anzac.
Basically every turn 1 empire gets nothing from lend lease, 1 gets about 1/2 the lend lease, 1 gets all the lend lease, and one roll can go any which way (statistically (some) money makes it to the allies most of the time).