Page Object Model and multiple locators with similar names

Perhaps you could have a locator for just label, and then have a function that clicks them based on a parameter, and then use that function in a parameter. I'm not 100% on how it works on .net, but something like this (apologies for syntax errors!):

private ILocator labels = _reportPage.Locator("label");

public async Task ClickNmt(int labelNumber) { 
  labelToClick = labels.Filter( new() { HasText = "NMT " + labelNumber.ToString() } ); 
  labelToClick.IsVisibleAsync();
  labelToClick.ClickAsync();
} 

public async Task ClickAllNmt() {
  for (int i = 0; i < 12; i++) {
    await ClickNmt(i);
  }
}

Perhaps for ClickAllNmt() i < await nmtCount or something like that if it's the amount of labels might change from 12 at some point

In JavaScript you could do i < await labels.count(), or possibly let labelsCount = await labels.count(); before it's needed in the loop

If you want a reason why not to do what you've done, consider what happens if you ever need to change the any of the ClickMntXX functions - now you'll have to change the same thing in at least 12+12 different places. Or you might mistype it at somewhere where you use it. It's also a bit difficult to read and increases the amount of code that one has to check for errors. It can be fine sometimes to repeat code, but in this case the code is very similar, so identifying the similar parts and writing something to handle those similarities is worth it.

The following is more general advice which likely doesn't apply in the code you are asking about.

It might be worth it to have 12 different objects (likely not locators) in memory in some cases, if the overhead of creating a new object was high enough and you needed to use those objects constantly, but I'll assume in this case it's not really an issue. If it was, some kind of array or dictionary containing the objects might be a good solution.

Thank you for taking the time to answer, much appreciated!

You could use a. All() on the label and pass in the filter, this will allow you to simply loop over the labels. Similar to the above example. I can add a snippet but currently AFK