The appliance of LAB in amide reduction
Very interesting question and not very obvious. As can be seen from the picture, LAB's reduce only tertiary amides. It is stated in the publication(1) about LAB reductions: 


  LAB reagents do not
  reduce primary and secondary amides even in refluxing THF.


In the same publication it is provided reason for different outcomes of reductions. They say that: 


  We found that the outcome of these reductions depends on
  the sterics of the amide as well as of the LAB reagent


Which means that if LAB and/or amide is sterically hindered it can't interact with nitrogen like in compound 5 

In lower part of the picture is described reaction where more hindered LAB leads to amine product 9



(1)Pasumansky, L., Goralski, C. T., &amp; Singaram, B. (2006). Lithium aminoborohydrides: powerful, selective, air-stable reducing agents. Organic process research &amp; development, 10(5), 959-970.