MaterialHandler.cs

using System.Collections.Generic;
using UnityEngine;

[RequireComponent(typeof(Renderer))]
public class MaterialHandler : MonoBehaviour
{
	static readonly Dictionary<string, Material> materialMap = new Dictionary<string, Material>();
	Renderer targetRenderer;
	
	public string materialPath = "Materials/pic";
	public bool asInstanced = false;

	Material GetSharedMaterial()
	{
		if (!materialMap.TryGetValue(materialPath, out Material material))
		{
			if (asInstanced)
			{
				material = new Material(Resources.Load<Material>(materialPath));	
			}
			else
			{
				material = Resources.Load<Material>(materialPath);
			}
			
			materialMap[materialPath] = material;
		}
		
		return material;
	}

	void ApplySharedMaterial()
	{
		if (targetRenderer == null)
		{
			targetRenderer = GetComponent<Renderer>();
		}

		targetRenderer.sharedMaterial = GetSharedMaterial();
	}
}