At my strongest, I remember getting winded walking up stairs. When I could move the most weight, my workouts took forever and the rest of my life lagged in the wake of fatigue.
Now, it is true that mass moves mass, but have you ever noticed how the strongest people in the world look kind of obese? They look out of shape or unhealthy? There's a reason, and for some that reason may actually limit their overall performance.
When I started training in the strength gym my buddy started last year, I started to notice how long the powerlifters took to do anything. Just deadlifting took 90 minutes to two hours. Then I realized why powerlifters always seemed to be out of shape:
They took way too long between sets.
Now, when we look at building maximum strength, the best recommendations provided for lifts above 85-90% of a 1RM is between 3-5 minutes depending on the athlete's ability to recover. What I noticed is that these powerlifters were resting 8-10 minutes between sets, and that contributed to them taking a long time in their sessions overall.
Now there may be benefits to resting that long, especially when it comes to being able to fully recover, but there's also downsides. Having to rest that long to fully recover is indicative of having a poor aerobic base, but also leads to not developing any aerobic base either. So force stays high, but metabolic demand stays low, and so body composition starts to increase.
With mass moving mass, gaining some of that weight can be a good thing. Your ability to handle maximal loads and create tension deep in the squat increases. A bigger chest decreases the range of motion needed for the bench press. The only thing that doesn't really seem to be benefitted acutely is the deadlift. But it also has it's downsides...
When we look at the body's ability to maintain overall health over a long span of time, fat deposits don't play in our favor. Especially if the fat stores we start to build up are visceral, which is the type of fat that surrounds your organs. This can cause complications with organ function, and can lead to some more serious side effects such as Type II Diabetes, and potentially some cardiovascular diseases. It also places more stress on your aerobic system, which is now put into overdrive when you do simple stuff like walk upstairs, leaving you out of breath.
Also, with long rest times, your aerobic capacity drops, making rest between sets harder long term, and decreases your ability to recover between workouts. Want to know why some of those CrossFitters can handle so much training volume? They have a great aerobic system, and so not only do they have a greater opportunity to recover between exercises or rounds of their workouts, but they have the ability to restore and replenish their body due to having better cardiac outputs.
So here's the deal, you need to rest between sets of maximal weight exercises, but you should be wary of how much time you're sitting around. Too much rest leads to some of the decreased metabolic demand, and long term may lead to more negative consequences. Keep on eye on the clock, rest enough to where you feel like you are pretty well recovered (notice I did not say full recovery), and then hit the next set. For maximal strength training, that looks like 3-5 minutes. For moderate strength training (70-85%) it looks like 1-3 minutes. And for hypertrophy work (bodybuilding style) it looks more like 1-2 minutes. If we start creeping up into the super high time frames, like 15 minutes (I've seen it), we probably need to reevaluate some of the life choices we're making.