Before commiting a wizard there is an option for 'Update Matrix Items and Matrix Parent?', this article will hopefully clarify this option:
If my wizard has one item contained within it and i am going to adjust the price as below:
I know this item exists within a Matrix, so the item in the wizard is the small, but there are also three other sizes of this product:
If i only want the wizard to affect the small i need to leave the tick box unticked, if however i want to change all the items i tick the box, in my example i am going to tick the box and commit the wizard:
When i then go back to the Matrix for this item we can see that the price has been changed for all of the items within the matrix:
NB: Wizards are processed sequentially, so will be 'queued' and processed one after another.