Pausing a script execution

Hello everyone

Let's say I have a loop instantiating blocks to form a map, and I don't want all the loop to happen in one frame, as it makes the program crash. Is there any easy way to pause the game execution for a couple of frames (let's say, instantiate 100 blocks on every frame rather than just trying to instantiate 1000 in one frame). I've done something like this, and, for testing purposes, I also added more delay, making each block spawn after 1 second.

The code looks like this:

 //Check the important edit below

So the point is this code isn't working at all. I've seen, though, that it causes refference errors when I want to iterate through a lot of blocks (more than 10,000) and it does nothing when working with a small 5x5 gameObject array. It seems I'm not implementing this right, so I'd like some advice on how it's done.

Thank you very much!

IMPORTANT EDIT:

Well, after some searching I've found a way which works for me, instead of making my method void, I made it return an IEnumerable object, and then used the "yield return WaitForSeconds(1.0f) inside of my code. Then, I call the metod which instantiates the map with the StartCoroutine function.

I've encountered some weird issues while doing this though:

As I said in the main post, this script instantiates blocks stored in an array. Those gameObject instances, come from another class, called AssetLibrary, in which I store all the block tiles classified by ID. So for some weird reason, the program works with small maps (i've tested up to 10x10) but it's not working for larger maps. The editor trows me this error message: "MissingRefferenceException: The variable blocks (this is the gameObject array where the map is referencing at) doesn't exist anymore"

The code looks like this:

 public class MapInstantiator : MonoBehaviour {
     
     public void ReadMap(string s) {
        // This reads the map from a text file and stores a refference for each tile of the array from another array stored in a class called AssetLibrary
     }
 
     public IEnumerator PrintMap() {
          for each block in map { //Pseudocoded
              Instantiate(block);
              return yield new WaitForSeconds(1.0f);
          }
     }
 }

And then in another class, i first call ReadMap and then i call StartCoroutine(PrintMap()).

It works fine for small maps, but it's not working for bigger ones, and I'm doing this so I'll be able to spawn larger maps so It's pointless to spawn a smaller one anyway.