If you keep a low infill, top/bottom layers will be rapidly more efficient but will cost more time and material than infill. The amount of wall is also to take into account. Few years back, I remember a test video showing that wall number were actually more efficient than infill. But depending how the test is being done, this might change.
For the test in question, top/bottom layers would help more than walls. I could see walls mattering more for different types of loading. Considering this video didn’t really see an increase in strength until 40% infill, one or two more top/bottom layers might actually use less material and result in more strength/rigidity.
If you keep a low infill, top/bottom layers will be rapidly more efficient but will cost more time and material than infill. The amount of wall is also to take into account. Few years back, I remember a test video showing that wall number were actually more efficient than infill. But depending how the test is being done, this might change.
For the test in question, top/bottom layers would help more than walls. I could see walls mattering more for different types of loading. Considering this video didn’t really see an increase in strength until 40% infill, one or two more top/bottom layers might actually use less material and result in more strength/rigidity.