Do what you will on your winter bike. Run all the spacers you want on either side of your stem. The rules don’t apply. On a summer rig however, that 2-5mm spacer between the top of the stem and top cap looks low rent. It looks bush. This is a proper expander bolt that doesn’t get machined with a metal lip that sits on top of steerer tube. If you have that lip, you need a spacer for the headset to function properly. So now all you need is a top cap to complete the transformation, and voila – stem slammed.