A working model that predicted values for magnetic fields throughout the solar system can be found here. Just because a given theory of why reversals occur has problems does not mean there is a paucity of evidence that they have occurred. The motion is not cumulative. It's apparent because it's really caused by the movement of the continents, not the poles. The cause is unknown, although it is thought to be due to some process in fluid motions in the Earth's core.
All pole shifts relate to the ice ages.
It could be due to planet size comets with a very long orbit of thousands of years. It is possible that they are still in orbit or have been captured by the sun and are now planets such as Mars. More recent research has proven that magnetic reversals were a very rapid phenomenom. Evidence for rapid magnetic reversals . The good news is, we all wander with it.