I've only ever used the call button once and even then, it wasn't me, it was the guy sitting in the aisle because he felt so bad for me.

I bought a snackbox (extremely short layover and I hadn't eaten yet that day) and as I was about to partake of my meal, the guy in front of me reclines his seat and my crackers go spilling to the floor (and this is in E+, no less). I had the sunbutter and jelly meal, so that meant my whole meal was basically on the floor. I snagged a FA as she was going by and asked for some extra pretzels so I could eat.

15 minutes go by and she never came back with them. That's when the guy in the aisle pushed the call button. 15 minutes later, a FA comes through with the orange juice/water (she didn't even acknowledge the call button). Aisle-guy asks for me again for the pretzels.

Another 20 minutes and a third FA comes by to see to the call button and I ask a third time for pretzels. She finally gets them for me pretty quickly.

Then again, I've had some flights where the FAs were more than attentive. As in life, it's hit-or-miss I suppose.