You can use any of the standard snap resolutions down to a 128th Triplet, which is 20 ticks (at 960PPQ). I was just trying to illustrate that there is effectively no limit to how fine a resolution you can get. Using ticks also allows you to set grids at non-standard resolutions like quintuplets, etc.
So, yes, showing 8th pool lines on a 4/4 timeline is no problem.