Just the opposite is the situation. Very little oil will reach the cylinders at idle due to the low airflow and low oil pressure. When the rpm's come up, the oil rushes to the intake manifold and the smoke will clear out the neighborhood.

Furthermore, you must be quite careful in making the determination that it "only smokes at idle". You can easily see the smoke at idle because the vehicle isn't moving. Once it starts moving through the air, the dispersion is significantly greater and your conclusion of reduced smoke might be false. It's necessary to clarify this point because all will be led astray with a wrong set of symptoms (very common on this forum).