Weird behaviour when required_score is exceeded

[Pedro David Marco via users]

Hi...
just a brief question.....   
i noticed that sometimes subtests are checked in a random way... weird! :-(  
sometimes they are checked, sometimes they are not.
Digging it out why, i have noticed that as soon as  score exceeds 
required_score, SA bypasses some subtests randomly, and final scores differs 
from one try to another.
 
This does not happen as long as required_score is not exceeded.
 
Any idea, please?
 
Thanks!
Pete.