Back during the infancy of this software, most people would use it for just two reasons: to store data (especially customer database) and as a glorified calculator. Perhaps because those are a spreadsheets intended or more practical uses or that people are not really that trained to use its features to the fullest. You would even be surprised that up to now there are office employees who, when they are prompted to make some calculations, they would open their spreadsheet software and do the calculations there. However, as weird as that may sound, it is one of the ways that a spreadsheet can help speed things up in the office. Especially if the employee has been working on spreadsheets for a long time that making fast calculations using the cells has become second nature to him. But there are other good uses for this application.
Nearly every strength and conditioning coach in the country relies on percentages to enforce desired intensities to athletes for certain lifts. Basically, the client would perform their lift at a percentage of their 1 repetition max. If they had a max bench press of 100lbs, and you wanted to do 3 sets of 12 reps at 60%, they would do 3x12 at 60lbs. This is absolutely necessary in most strength and conditioning environments for multiple reasons, including consistent program design as well as enforcement of intensity (speaking from experience, some people WILL slack if given the chance). So the question becomes, are percentages right for you?