One of the cornerstones of building high quality muscle is time under tension. Think of this as the time associated with some of the hardest parts of a rep. In simple terms I like to look at it as "up" "down" and "holds"
The tempo that I have been enjoying lately is a 1 to 3 tempo. 1 up, 3 down, and a hold for a sec either at the top or the bottom of the rep.
Let's take a bench press - this would mean 1 second to press the weight up, 3 seconds on the way down, and then pause for 1 second on the bottom while it's resting on your shirt.
Slow is king but it takes high focus and will result in more time in the gym (in certain cases).
As stated earlier I have been doing this time method on my more high rep days because it builds incredible discipline as well. It's mental work on top of physical work - my kind of style.
Stay rad,
Chris