Lowering a dumbbell 6 times a day offers significant gains in strength
newatlas.com
newatlas.com
I think this started when crossfit style programs gained popularity. It's all about pumping out as many reps as possible in the shortest amount of time.
While that's good for elite athletes who compete in the sport. For the general gym-goer it's just asking for injuries to happen.
Before anybody undergoes any major lifestyle change, for the love of fuck, listen to the warnings about checking with your doctor, you might be glad you did.
The key is to extend the lowering(/lengthening aka "eccentric") time. 4 seconds is a minimum, but "extreme eccentrics" (30+ seconds) are even more effective.
Based off knowing low reps do more to increase strength and high reps increase size.