Not at all. Stepping through a function with a debugger usually takes on the order of seconds and minutes. Printing some stuff in the function usually takes on

Not at all. Stepping through a function with a debugger usually takes on the order of seconds and minutes. Printing some stuff in the function usually takes on the order of microseconds or milliseconds. That's a difference of at least three, possibly eight or nine orders of magnitude. It's very easy to imagine a timing-related issue that's affected by a delay of X seconds, but not a delay of X microseconds (RPC calls are typically on the order of milliseconds, for instance).