Flex Friday: Why You Should Go For A Pump & Flex
Are the meatheads right about this one? I would say so! The more you go for a pump and flex those muscles, the better your mind-muscle connection...This typically is a huge component in growing muscle. So what gives? Do you have to be douchey and flex after every set? Not necessarily, but you should develop some sort of checklist to ensure you are doing the most to build mind-muscle connection and the pump is a great indicator.
Here it is.
1. Do I get a pump in the muscle when I do this exercise?
Yes? The exercise works for your limb length ( no single exercise is king ), continue with it!
No? Either your form is off or you may be better suited for a change of exercise. For myself, a dumbbell bench has always felt better than a barbell bench for my chest.
2. Do I like the exercise?
You will typically try harder in an exercise you enjoy more. Sometimes the lack of interest will lead to a lack of focus, go figure. Do exercises you actually enjoy, there is plenty of variations out there.
3. Slow it down!
Often people will rush through their exercises with zero focus on the stretch and squeeze, turning it into a more "joint" centric exercise. This probably sounds dumb to the smart exercise people, but let me explain.
If I squat as far as I can, yes my muscles are still stretching at a rapid rate and working. However, my lack of mobility in my calves prevents me from hitting the desired depth without my lower back rounding. When you slow it down, you can maintain a level of tension that is missed during these rapid movements. As well, as plenty of science to show the benefits of constant tension in its relation to muscle growth.
Doing exercises you like with proper form and resulting in your muscles looking better is a pretty simple explanation of what drives muscle growth. However, people get tricked into certain exercises and ways of training because of their perceived benefits. Do what you want, this is just my opinion.

Be smart, and train hard!