That tip probably should be re-worded a bit. It does kind of make it sound like the bars effect has that ability. Bars do not have the start and end intensity sliders. If you layer the on effect on top of the bars, you can use that as a way to control the start and end intensities. Make sure you set the blending option of the on effect to "1 is unmask", start intensity 0%, end intensity 100%, and make sure the cycle count is set to 1, and you have a color selected (doesn't matter which color since it's a mask).