A better practice would be to pass arguments inside your functions:
The first one will be received in 24/r25, second in r22/r23, third in r20/r21, and fourth in r18/r19.
he's advocating the opposite of what I recommended a while ago. Using a standard argument calling convention is definitely "better practice." Using customer argument calling conventions can save you space. As you're finding out, it also can cause difficult-to-find bugs.