It is often a car park on the M1 from 6am until 9am heading north, and from 3pm until 7pm heading south. If there has been a car accident, it can also be a car park at any other time.
On weekends it is often slow heading south in the mornings and north in the afternooons.You need to allow plenty of time, and check your smart phone maps app for current traffic conditions.
A friend drove from Ballina to Brisbane Airport this morning and it took them nearly 4 hours - a trip that would normally take 2 hours. They ran straight into peak hour traffic and there were no incidents but the trip still took nearly double the normal amount of time. Either do the drive out of peak periods, or wait until the weekend.