Is it a bad practice to always instantiate Prefabs from script references? - unity3d

Question

Whenever I need to instantiate prefabs, I always use the following technique
Add a GameObject/MonoBehaviour field to the MonoBehaviour which would instantiate the prefab.
Use this field to instantiate the prefab
E.g.:
public class ExmapleController : Monobehaviour
{
[Serializefield]
GameObject _examplePrefab;
GameObject _exampleObject;
public void SpawnExample()
{
_exampleObject = Instantiate(_examplePrefab);
}
}
Now my problem with this is that first of all I need two references. One for the prefab and one for the instantiated object. Secondly, whenever I need additional prefabs I have to create new and new references inside my script. This sometimes clutters my Scripts and I always wonder that is this memory efficient? What does Unity do behind the scenes? It just only stores a GUID reference for my prefab than somehow loads this prefab based on this reference? Or when I make a prefab reference the whole object tree is pulled into memory and I should rather use Asset bundles or another Unity technique?

Answer 1

Basically that's fine. But if you want to improve your workflow you can try creating ScriptableObjects to store the prefab references and then have only 1 reference to your scriptable object inside the mono behaviour. It will help you keep your mono behaviour classes clear. For more advanced approach you can check Dependency Injection frameworks for Unity. The most common one is Zenject. It helps you in managing dependencies in your classes (prefabs in your case are dependencies of Monobehaviour class).
When you create a reference to a Prefab Unity only store the GUID of the prefab you referenced. It is how resource system in Unity works. But if your prefab is required on the current scene then it will be fully loaded with all inner dependencies. If loading takes much time than it is the reason to think about using Addressables (AssetBundles). Unity doesnt have any other technique to avoid loading the full object tree in memory. But addressables let you control when to load the specific prefab from asset bundles to memory.

Answer 2

Yes this perfectly fine and how it's done. A reference is just that: a reference. The only time a copy of the object is made is when you call Instantiate.
If you have multiple prefabs that are just variations of one you should use ScriptableObject instead and have just 1 prefab that can take any variation form. You would still intantiate them the same way.

Answer 3

Basically that's fine. But if you want to create a huge numbe of objects or delete them you could also have a look at Object Pooling. More infos can be found under the link from the tutorial at Unity:
https://learn.unity.com/tutorial/introduction-to-object-pooling#
"Object Pooling is a great way to optimize your projects and lower the
burden that is placed on the CPU when having to rapidly create and
destroy GameObjects. It is a good practice and design pattern to keep
in mind to help relieve the processing power of the CPU to handle more
important tasks and not become inundated by repetitive create and
destroy calls. (Unity)"