Are you using the Park Tool chain measuring gadget or a ruler? I've seen the Park Tool chain measuring gadget indicate that chains are seriously worn when a ruler indicates that it's just fine.

Pin to pin is exactly 12" on a brand-new chain. Generally if you're replacing the chain before the 12 1/8" mark, you'll be ok. There's an excellent article here: https://www.sheldonbrown.com/chain-wear.html that explains in detail what's occurring.

I find it difficult to believe that you could ruin a chain in four weeks unless you were really trying