any way to scroll presets one at a time instead of like 30

Why not limit the number of presets you have. You can do that a couple of ways.

Turn on or off certain catagories of the presets you have. You do that by right clicking anywhere in the Preset list area and selecting "Manage Presets". 

You then get this dialog box where you can turn on or off groups of presets.

You can also Delete and or Move presets out of the LR default Develop preset file location. you can get there through the LR Preferences, Preset tab.

And you can Collapse the sections, Groups, that you don't want to use on a photo as I have shown above. I have all sections collapsed. Click the right facing triangle to expand them and again to collapse them. That way you don't have to search all of them for the one/s you are thinking about applying.

I only need to hover the mouse cursor over the Preset names, and move the mouse (no button press), to get the previews of all the presets that the cursor travels over as I move down the panel. I do not even need to use the scroll wheel. (Note: there is a Preference/Performance/Develop option that can turn 'on/off' the full window preview)

Creating sub-folders ("Groups") in the preset panel needs a workaround-  Create any Preset [+], in the 'Group' field select [New Group...] and give your Group a Name (ie. a 'sub-folder' name). Now you can drag any User presets into this group to organize.

Groups cannot be empty! (delete all presets from a Group and the Group also deletes).

Even better is to organize your Preset files in the OS File Browser and use a Plugin by John Ellis to convert your File sub-folders into Preset Groups.

Fix Presets Lightroom Plugin