Coaches often discuss the optimal rest intervals between sets for various training objectives. One common “rule of thumb” is that for maximal strength you want “complete” rests, and for hypertrophy you need “incomplete” rests between sets.
HOWEVER: You can never allow yourself to recover fully between sets, because if you rest long enough to remove all traces of fatigue, you’ve also rested long enough to remove all traces of the neural drive that accumulated from previous sets. So the trick is to find the “sweet spot” on that continuum, where fatigue has been diminished, yet where you’ve still got some neural drive remaining from previous work.
One of the most significant epiphanies I’ve had about my own training is that, being fairly average on the fiber-type ratio, I don’t need as much rest between sets as I’d intuitively think. Here’s why: if you’re neurologically superior (predominantly fast-twitch) you’re tapping into a much higher percentage of your true potential when you lift heavy…therefore, you need longer rests. BUT, if you’re a slow-twitch dominant geek like I am, whenever you lift “heavy,” it’s not really as high a percentage of your capacity as you think. So, 1) you don’t really need the rest, and 2) if you rest too long, you’ve lost a good bit of the neural drive that you so preciously need.