For rep ranges there really is No one right answer, but yes it does depend on goals. Allow me to explain. If you had a power lifter, then yes they would work in low rep ranges, with high weight on their main lifts, but higher reps on other lifts. And if you had a strength lifter then they would work in the 3-5 range on the core lifts, and higher reps elsewhere… and then there is everyone else. And as recent evidence from Brad Schoenfeld and others has conclusively shown, one can develop hypertrophy regardless of the rep range so long as the muscle is exerted to near failure for several sets. Ergo it is muscle fatigue that is the key, not the rep range. So to play is conservative and safe I have clients work in a range of 8-12 in the beginning to develop better form. lastly, reps do no dictate muscle size, or bulk.. eating does. You can train with low or high reps all you want but if you dont enough, or too little no change will happen.