Practice makes ALL the difference in these type of tests
Having never used an aptitude testing software to practice with I can only repeat what others, who have purchased PILAPT software and used it to practice with have told me; whilst the increased familiarity with the types of tests you may undergo during selection for a job/FTO placement helps with confidence and can improve your performance... it is not by a margin that would make much of a difference.
The People that create tests such as PILAPT claim that you will either be good at them or you wont, simple as that. Of course there might people that are an exception to these claims, who knows.