Remember doing an exercise where you have a sudden burst, jolt yourself and give your 100% at the moment? Like, say sprinting. You sweat within minutes, start puffing, get tired. You feel great! You must have burnt quite a few calories. Or at least you think so.
Big shakeups, the act of moving fast, intense activity, and immediate exhaustion give us a cue that we are working hard. But don't you get tired quickly? How long can you sprint? What's the effective volume of the exercise?
Now think about doing something that doesn't seem so frantic or even effective at the moment. Like, say squats(not the best example but I hope it drives the point home). First 40 reps hardly have any effect. You don't feel it. No puffing, you doubt if you are doing any exercise at all, it seems easy. Then each rep starts hurting a bit, but not so much that you quit on the 42nd rep. It burns slow. You do another 20, your muscle burns a bit and you stop. Within a couple of minutes, you feel replenished enough to do another 20.
The good part is you can sustain this exercise for way longer than a sprint, you can spend more time doing it. You are probably not burning as many calories right there, but it results in more significant muscle breakdown and the body continues to burn calories even after the workout.
Likewise in life and business, we give more importance to big, fast moves that seem like an intense activity because they have immediately visible consequences, like sweating. But they don't necessarily produce effective outcomes. Moving fast is overrated.
Moves that are seemingly slow but build on each repetition are way more sustainable. You get enough time to take feedback, make corrections and do it properly. You can produce higher volume. Avoid burnout. Move slow to effectively move fast.
The slow burn is not an excuse for laziness though. It needs more time, more work but disguises itself as seemingly easy, so much so that people don't consider it effective. Slow, deep burn results take time but are more lasting. The magic is in the reps.