Less so they could give them a break, and more so they could catch up after filming on the initial three episodes went way longer than originally scheduled...But then another reason for the Doctor-Lite episodes is to give Doctor and companion a bit of a break. Example in season 1 the main reason Adam tagged along in The Long Game was so they could have him off doing his own subplot with guest actors and give Eccleston and Piper a break.
Or they simply commissioned scripts so that they could double-bank if they needed to (as had been done in all four previous series).I would guess giving Karen Gillan a break was a similar reason for why in season 5 we had the Amy-lite The Lodger.