You might as well as me have wondered, why there are vertical grid lines on the chart without a configurable interval and actually this is the first thing I turn off when I open a clean chart. There is a whole bunch of tools that you can use for displaying vertical grid lines with specified interval, but this is actually a pretty basic thing that should be on every chart without an external indicator. With Rainbow (although it is an external indicator;) you can have this out of the box. Just look for the “Vertical grid-lines interval” parameter and enter the number of minutes. As simple as that.