Photoshop action to group every 4 layers?

Are all the Layers top-level or are existing Groups involved? 

Here is a script, it prompts for the number of layers to group. This could be hard-coded into the script if it was always 4.

This script needs to be run multiple times, so if there were 8 layers, the script would be run twice. 

/*
https://community.adobe.com/t5/photoshop-ecosystem-discussions/splits-layers-and-puts-them-into-groups/td-p/13211952
by Charu Rajput
*/

deSelectAllLayers();
var layLength = activeDocument.layers.length;
var _layers = app.activeDocument.artLayers;
var _name = prompt('Enter number: ', layLength);

if (_name) {
    _groupLength = Number(_name);
    if (!isNaN(_groupLength)) {
        if (_groupLength !== 0 && _groupLength <= _layers.length) {
            for (var i = 0; i < _groupLength; i++) {
                selectLayerByID(_layers[i].id, true);
            }
            groupSelectedLayers(_name);
        } else {
            alert('Either you entered 0 or entered number is higher than the number of layers present in the document');
        }
    } else {
        alert('Enter value is not the number');
    }
}

function groupSelectedLayers(theName) {
    var desc159 = new ActionDescriptor();
    var ref114 = new ActionReference();
    var idlayer = stringIDToTypeID("layer");
    var idordinal = stringIDToTypeID("ordinal");
    var idtargetEnum = stringIDToTypeID("targetEnum");
    var idnull = stringIDToTypeID("null");
    var idname = stringIDToTypeID("name");
    ref114.putEnumerated(idlayer, idordinal, idtargetEnum);
    desc159.putReference(idnull, ref114);
    desc159.putString(idname, "aaa");
    executeAction(stringIDToTypeID("groupLayersEvent"), desc159, DialogModes.NO);
    var desc63 = new ActionDescriptor();
    var ref37 = new ActionReference();
    ref37.putEnumerated(idlayer, idordinal, idtargetEnum);
    desc63.putReference(idnull, ref37);
    var desc64 = new ActionDescriptor();
    desc64.putString(idname, theName);
    desc63.putObject(stringIDToTypeID("to"), idlayer, desc64);
    executeAction(stringIDToTypeID("set"), desc63, DialogModes.NO);
}

function selectLayerByID(index, add) {
    add = undefined ? add = false : add;
    var ref = new ActionReference();
    ref.putIdentifier(charIDToTypeID("Lyr "), index);
    var desc = new ActionDescriptor();
    desc.putReference(charIDToTypeID("null"), ref);
    if (add) desc.putEnumerated(stringIDToTypeID("selectionModifier"), stringIDToTypeID("selectionModifierType"), stringIDToTypeID("addToSelection"));
    desc.putBoolean(charIDToTypeID("MkVs"), false);
    try {
        executeAction(charIDToTypeID("slct"), desc, DialogModes.NO);
    } catch (e) {
        alert(e.message);
    }
}

function deSelectAllLayers() {
    var idselectNoLayers = stringIDToTypeID("selectNoLayers");
    var desc26 = new ActionDescriptor();
    var idnull = charIDToTypeID("null");
    var ref3 = new ActionReference();
    var idLyr = charIDToTypeID("Lyr ");
    var idOrdn = charIDToTypeID("Ordn");
    var idTrgt = charIDToTypeID("Trgt");
    ref3.putEnumerated(idLyr, idOrdn, idTrgt);
    desc26.putReference(idnull, ref3);
    executeAction(idselectNoLayers, desc26, DialogModes.NO);
}

https://prepression.blogspot.com/2017/11/downloading-and-installing-adobe-scripts.html

EDIT: Here is a modified version to loop over all top-level artLayers so that it is fully automated. There is no error checking if there are more or less than 4 evenly divisible layers, so if there are "left over" layers they will remain ungrouped.

for (var i = 0; i < activeDocument.artLayers.length; i++) {
    layersToGroups();
}

function layersToGroups() {
    /*
https://community.adobe.com/t5/photoshop-ecosystem-discussions/splits-layers-and-puts-them-into-groups/td-p/13211952
by Charu Rajput
*/

    deSelectAllLayers();
    //var layLength = activeDocument.layers.length;
    var _layers = app.activeDocument.artLayers;
    //var _name = prompt('Enter number: ', layLength);
    var _name = 4;

    if (_name) {
        _groupLength = Number(_name);
        if (!isNaN(_groupLength)) {
            if (_groupLength !== 0 && _groupLength <= _layers.length) {
                for (var i = 0; i < _groupLength; i++) {
                    selectLayerByID(_layers[i].id, true);
                }
                groupSelectedLayers(_name);
            } else {
                alert('Either you entered 0 or entered number is higher than the number of layers present in the document');
            }
        } else {
            alert('Enter value is not the number');
        }
    }

    function groupSelectedLayers(theName) {
        var desc159 = new ActionDescriptor();
        var ref114 = new ActionReference();
        var idlayer = stringIDToTypeID("layer");
        var idordinal = stringIDToTypeID("ordinal");
        var idtargetEnum = stringIDToTypeID("targetEnum");
        var idnull = stringIDToTypeID("null");
        var idname = stringIDToTypeID("name");
        ref114.putEnumerated(idlayer, idordinal, idtargetEnum);
        desc159.putReference(idnull, ref114);
        desc159.putString(idname, "aaa");
        executeAction(stringIDToTypeID("groupLayersEvent"), desc159, DialogModes.NO);
        var desc63 = new ActionDescriptor();
        var ref37 = new ActionReference();
        ref37.putEnumerated(idlayer, idordinal, idtargetEnum);
        desc63.putReference(idnull, ref37);
        var desc64 = new ActionDescriptor();
        desc64.putString(idname, theName);
        desc63.putObject(stringIDToTypeID("to"), idlayer, desc64);
        executeAction(stringIDToTypeID("set"), desc63, DialogModes.NO);
    }

    function selectLayerByID(index, add) {
        add = undefined ? add = false : add;
        var ref = new ActionReference();
        ref.putIdentifier(charIDToTypeID("Lyr "), index);
        var desc = new ActionDescriptor();
        desc.putReference(charIDToTypeID("null"), ref);
        if (add) desc.putEnumerated(stringIDToTypeID("selectionModifier"), stringIDToTypeID("selectionModifierType"), stringIDToTypeID("addToSelection"));
        desc.putBoolean(charIDToTypeID("MkVs"), false);
        try {
            executeAction(charIDToTypeID("slct"), desc, DialogModes.NO);
        } catch (e) {
            alert(e.message);
        }
    }

    function deSelectAllLayers() {
        var idselectNoLayers = stringIDToTypeID("selectNoLayers");
        var desc26 = new ActionDescriptor();
        var idnull = charIDToTypeID("null");
        var ref3 = new ActionReference();
        var idLyr = charIDToTypeID("Lyr ");
        var idOrdn = charIDToTypeID("Ordn");
        var idTrgt = charIDToTypeID("Trgt");
        ref3.putEnumerated(idLyr, idOrdn, idTrgt);
        desc26.putReference(idnull, ref3);
        executeAction(idselectNoLayers, desc26, DialogModes.NO);
    }
}

It is possible, however, it is not elegant or bullet proof. You need to use relative keyboard shortcuts to select layers rather than selecting layers with the mouse.

Relative Layer Keycuts:

Select/target front (top) layer = Option + .
Select/target next layer up = Option + ]
Select/target next layer down = Option + [
Select/target back (bottom) layer = Option + ,

(For Windows, swap the Option for Alt)

You will also need to hold down the shift key when selecting the 4 layers to group.

A script would be better as it can use conditional logic. For example, what if the length/count of the layers is not evenly divisible by four?

A lot will depend on the structure of your layers and their visibility, also consistency between files will have a major impact.

Can you provide a screenshot of your layers panel?

Edit: This action groups 4 sets of 4 layers, so it must be run on a doc with 16 layers, otherwise the results are not as intended.