You can also do the patch before the hole actually wears through - even just stitching over the top of the thinning area is probably enough to provide extra reinforcement to stop the hole forming, although the extra fabric provides a more stable base for the new stitching.
Darning and patching are popular topics in the raw denim community. One of the draws of raw denim jeans is that they're typically made of heavier weight fabric and don't come pre-faded or pre-shrunk, so with proper care they can last a lot longer than big box fast fashion jeans. They're also usually produced by small makers from all over, so it can be a great way to buy local. Of course the downside is that they're many times more expensive than what you'll find in department stores.
Some denimheads like to get creative with eye-catching thread colors, patch fabrics, and darning patterns. Coupled with the exaggerated fading patterns that can be achieved with raw denim, it's really neat to see!
It's not, the fabric is actually quite light so I can't feel it at all. I would avoid using a heavy denim though, I have used that on a knee patch before and it was too heavy.