The wall of links that Jim mentioned above is here:

https://forum.profantasy.com/discussion/10366/cartographers-annual-all-the-issues-linked-in-one-place

That's a good idea too.

Most CC3 dungeon styles are top view orthographic, so you would only ever see the wall and not any part of the face of it, so it's quite rare to get such symbols.

Yes, I remember there being something myself but I can't find it now either. We must both be using the same 'wrong' search words.

But never mind - I can possibly help you here.

Make a new sheet immediately above the one with the repetition issue (under it in the sheet listing because the sheet listing is upside down to most people's way of thinking).

Either:

1. use one of the semi transparent fills (denoted by having a 'T' in the fill name in DD3) in patches on that sheet, or
2. add an Edge Fade Inner sheet effect to the new sheet, and then draw patches of similar textures on that. When you refresh the drawing the EFI will blend the edges into the old sheet.

It's more effective to use similar textures rather than the same one. For example if you have several shades of grass use one of the other shades of grass to patch the original grass.

It can take a little practice to get the second method to work correctly, but I've found it more effective than the first one.

...

EDIT: It is also worth remembering that repetition becomes far less obvious when there are more objects in the map, so if you are staring at just the background with nothing else at the beginning of a map you will inevitably see the pattern. It might be worth finishing the map before you decide to go through the process of patching.

Yes, that's very true.

@HelenAA - Joe's recommendation will also prevent the 'fly away' artefacts you can sometimes get when smooth nodes are more or less on top of one another, for example when converting a more extreme fractal line or polygon.

That old hatched stone fill seems to be stuck in the DD3 repertoire, but there are other alternatives around. If you are looking for something reddish you could use one of the Dirt fills instead, or maybe the "Stone Lava Cooled" and a sheet effect to change it's colour to something more reddish.

If you have other add ons there's no reason you can't use a fill from one of them if there's one you would prefer. How you do that is use Insert File in the Draw menu and pick a pre-prepared blank map of that style (or the actual template file .FSC) and press ESC just before clicking to place it in your map. That will import just the fills for that style which you can then use in your map.