That's a regional/local choice. In my area, we have a number of signaled crosswalks which never activate unless someone pushes the button. They are absolutely

That's a regional/local choice. In my area, we have a number of signaled crosswalks which never activate unless someone pushes the button. They are absolutely instant. They're not traffic signals, though, they are a dozen or so strobing yellow lights. It's effectively a red light based on local law, but it's way more noticeable for approaching traffic.