Measuring Efficiency
The most efficient reaction is where every electron added is used in the reaction, in the way you intend. In reality, more than 1 electron equivalent is required to drive a reaction to completion, with the efficiency of the reaction being calculated from the theoretical optimum and the observed behaviour. To calculate the efficiency requires you to measure your starting material or product concentration, giving conversion efficiency or yield efficiency, respectively. It is not something you will know at the outset.
You will be familiar with the concept of conversion or yield as indicator of your reaction progression. This modeller allows you to explore the concept of efficiency. Although this is a batch process, during the reaction current is constantly flowing - in effect you are adding one of the 'reactants' continuously. At any point in the reaction you can calculate the efficiency by comparing the actual conversion of starting material (or formation of product) to the delivery of electrons. This goes hand-in-hand with the more established measure of %conversion or %yield.
The first modeller gives you a measure of efficiency of conversion whilst the second gives you efficiency of yield. The modeller allows you to say what concentration you have achieved after a given time point, and at that time point compares what could theoretically have been achieved assuming perfect efficiency (i.e. each electron is part of the reaction you intend)
In the early stage of reaction, the efficiency might be different than that achieved later on where competing side reactions may have become more important, so be sure to include at what point you are reporting your measure of efficiency. Also remember, a low efficiency might mean you have run your reaction too long, since you are continually passing electrons through the circuit- converting all the starting materials and then supplying other reactions such as the decomposition of solvent, or producing heat!