Leaven was wrong about the trap rooms being prime numbers, so...
**SPOILERS**
Was it just a coincidence that they didn't run into traps when she thought she had the pattern figured out?
Because they realise later on in the movie that the real way of finding a trap room is by figuring out the number of factors of the primes, not the actual prime numbers themselves.
She must have been wrong the first time, so it would've still been completely random whether or not they find the traps. Just seems ridiculous to me that they got through so many rooms just by sheer luck until they realised the mistake.