Just curious, do you do any "leg extensions"?
"These researchers also found that open-chain exercise (leg extensions) produced more rectus femoris activity while closed-chain activity (squats) increased recruitment of the larger, more powerful vasti muscles
Ask anyone "in the know" and they'll tell you that rapid and strong vastus medialis recruitment is imperative for knee health — and VMO function is the first thing to go in the presence of knee injuries. Why would we want to do an exercise that promotes delayed firing of the muscle?
Moreover, the rectus femoris is an extremely common cause of knee and hip pain in lifters due to excessive trigger points and poor flexibility; the last thing it needs is more direct work! What it does need is lots of soft-tissue work (foam rolling, massage, ART) and dynamic and static flexibility attention."