The job interface allows the caller to specify a time out with all test functions. This determines how long the test function is allowed to block before returning if no operations of interest have completed.
The lower level APIs follow different semantics. Rather than a time out, they allow the caller to specify a max idle time. The max idle time governs how long the API is allowed to sleep if it is idle when the test call is made. It is under no obligation to actually consume the full idle time. It is more like a hint to control whether the function is a busy poll, or if it should sleep when there is no work to do.