Is it possible to have foundations repeat fewer times?

I'm only just seeing your question, but yes it is possible, you just have to adjust a setting in Warehouse Mode for each texture. It's best to do this while you have only one texture in the package, adjust it, then add more swatches so the settings carry over.

So, in Sims 4 Studio Warehouse mode, find the Material Set line on the left, and ensure you're under the Data tab on the preview pane on the right. Click Edit Items next to Entries. You will see some Diffuse texture reference files, and will have to update this for each one, which is why you want to work while having only one swatch or you will see a multitude of entries to change. Click on the first one to highlight it, then on the right window pane, click Edit Items again next to the Items tab in Material. Look for the DiffuseUVScale line, and adjust the numbers [0] for horizontal, and [1] for vertical. If you lower the numbers, this will cause a larger texture to spread across multiple panels. For example, when I make a wallpaper mural, I reduce the [0] depending on the size of my texture that I want to cover multiple panels. So, if I have a texture that I want to cover 4 wall panels, I would change the [0] (horizontal) from 1 to 0.25, 3 wall panels to 0.333, 2 panels to 0.5. The textures have to be sized accordingly. For a 4 panel texture, it needs to be 1024 pixels wide, 3 panels 768 pixels, and 2 panels 512 pixels wide. Click SAVE at the bottom of each window and save your package to test. Once you figure out if the texture is right, then add more textures using the Add Swatch button in Studio mode.

I don't recommend adjusting the vertical setting [1] because this will cause your textures to tile incorrectly, unless it is truly seamless vertically. This is not good if you have a border on your foundation texture.

You can play around with these numbers to see the effects in game. I hope this helps.