Should I aim to score 100%?

CareerSet should be used in a pragmatic way. It should not be your aim to reach a score of 100%. 

Although our algorithms have been tested via hundreds of thousands of CV uploads to date, there may be small variations and inaccuracies in the scoring of individual CVs. Therefore, aim for a score of at least 80%, use the advice which you deem relevant and disregard that which isn't.

Scores are not used for any other purpose than to give you a benchmark of where you stand in terms of the impact, presentation and style of your CV.