I’m sorry to read that week 2 gave you a hard time @duerer. It looks to me like you’re focusing too much on high frequency detail and not the broader shapes like scraping off the hard, perfect edges in favor of a hand-chiseled look. Here’s a quick video of me sculpting a few of your chimney stones:
90% of this is only the Scrape brush chiseling the perfect, uniform blocks into imperfect, hand-made versions. I also used the Crease brush to vary the depth of the crevice between blocks. The goal here is “handmade” and “imperfection”.
Once you achieve these broad accents, you might not even need high-frequency texture detail like you were pursuing. That tends to look too realistic anyway.