I took the SIA aptitude test in May 2000. With so many difficult tests I took before graduating Embry-Riddle Aeronautical University, I only expected the worst and was apprehensive.
However, the 3-4 hour 20 or so segment test was damn easy provided all one had to do was focus and answer the questions. Anybody over age 16 that is focused can pass it, that is once again anybody focused. Nothing to worry about.
The nightmare is the tea party interview, not the aptitude test. Good luck.