Recently, I have practiced 10-20 hours of clay farming for the Skull Cavern Level 100 Speedrun, is there only one pattern?
The one discovered by piano addict? Is there no single other one?

I think there is a better one Piano found. I'd suggest checking out his Discord (or streams) or joining the SDV Speedrun Discord to ask about it. Information is often there or can be asked about. Clay farming info is often passed on through streams (I learned from Bulltg's youtube video).

You can use regular farming methods as well to get the money needed (using sprinklers). I did clay farming mostly because I just wanted to try it and see if it would be viable.

Chick It's pretty much so, viable, saves so much time specially with coffee. I would really appreciate any links to streams and yt videos of patterns that are different than BullTG's one
Edit:- If you want you can see my progress on my skill on Clay Farming,I can give a video or something,I really think the method I use is not just the best

If you just search twitch for Piano/pianoaddict (something close to that) you'll find his stream fine. A few others do use it sometimes like Lichatton.

For videos/vods, I'd suggest just going to their stream and asking there. If anyone has an idea of which vod it'd be it would be the streamer themselves. Piano might also demonstrate it if he has the free time. Generally though should try digging in their stream history for anything labeled clay farming (or Joja)