The tried-and-true rep scheme for hypertrophy is 10-12.
The tried-and-true rep scheme for building strength is 3-5.
A combination of both these is best.
Very high reps (15-20) are sometimes incorporated into programs to bust through stalls in training, but still at a challenging weight. If by "low weight" you were meaning 3-5 pound DBs, for instance, then no. That weight is not challenging to do anything to anybody, evenm doing 100 reps.
If it doesn't challenge you, it doesn't change you
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| current weight: 111.8