If as is the case in point the pieces are 2.5 inches each and you have 11 inches you can have them jam up together and get 4 rows and a one inch piece left or you can spread them out to 0.2" apart and not have any left, in either case you have 4 rows and have not lost the ability to get any more pieces, just that your scrap is smaller, but the pieces have a chance of looking better.
You are right, it is very easy. However, from someone who has not used Inkscape before or any digitial design, there are multiple terms to comprehend. Just understanding that a 1 in the field gives you 100% translation of the bounding size. Complex actually given that there are seven tabs and then what the transformations in the symmetry tab actually do.