The stopwatch leaves things out
Ten repetitions lasting six seconds each produce sixty seconds of movement. Ten repetitions lasting three seconds each produce thirty. That arithmetic is correct; the conclusion that the first set produces twice the adaptation is not.
The slower set may require a lighter load or fewer repetitions. The comparison therefore changes several features at once. Time alone does not describe the force the muscles produce throughout the movement.
A pause can have a practical purpose
A brief pause may make a position easier to notice or reduce reliance on bouncing. Controlled lowering may help someone learn the movement. Those are useful reasons without needing a claim that one precise tempo is optimal for everyone.
“I used a slower lowering phase to keep the movement consistent” is a clearer explanation than “slow repetitions always build more muscle.”
Moving slowly and trying to move fast differ
A heavy load can move slowly despite a strong intention to accelerate it. Deliberately slowing a light load is a different task. Describing both as “slow training” hides that distinction.
When you change tempo, record it. A lower repetition count under the new condition does not necessarily indicate lost fitness; it may simply reflect the changed rules of the exercise.
