Interesting behaivor of TESTNET difficulty

[n0nce]

You can see this most recently happening just a couple of months ago at epoch 1,212. Epoch 1,211 took 12 days, 2 hours, and 42 minutes. This is 290.7 hours, which would be 1744.2 blocks. 2015/1744.2 = 1.156. And so if you look at the difficulty for epoch 1,212, it is 1 * 1.156 = 1.156.

You're right; there are more big difficulty drops, I just filtered out the ones that went to exactly 1. Many, many more drops went to < 100 or < 1,000.

We can compare with mainnet here: https://blockchair.com/bitcoin/charts/difficulty
It never really significantly drops.

[vjudeu]

Jameson Lopp wrote about that, x4 difficulty and why 1 difficulty is regularly occurs for testnet blocks.

https://blog.lopp.net/the-block-storms-of-bitcoins-testnet/

functionality for developers to run "signet" test networks that don't use mining at all, but rather use a federation of block signers

Very interesting. That means, signet was supposed to contain signing-only, without even CPU-based mining! Which means, my comparison between federations as a sidechain of Bitcoin is even more relevant than I supposed. Because that means, signet could be deployed on top of testnet3 as well, and just be based on signing blocks to prevent blockstorms! Which means, signet could be just a testnet3 soft fork, that could add signatures into blocks, based on signetchallenge! I wonder, why it was not deployed in that way. Is it only because of blockstorms?

Also, I can imagine testnet3, as a base for any signetchallenge, in that way it could be even a no-fork, where some signet could simply read data from testnet3, and reuse those coins in a more stable environment. Then, everything would be double-confirmed: first by signet signatures, and then by testnet3 Proof of Work. I am curious, how such model would behave in the wild.

[d3bt3]

Before to all i want to remember to everybody that TESTNET coins are worthless and never supposed to have any real value.

They are worthless because you can not trade Bitcoin Testnet on exchanges but in aspect of Bitcoin miners and developers, they are very valuable.

In aspect of development, Bitcoin testnet help developers a lot.
In aspect of Bitcoin users, it is helpful too because they can practice with Testnet without capital loss.

More interesting, in aspect of Bitcoin miners, they have to spend cost, ASICs to mine Bitcoin testnet that actually has intrinsic value input.

You very well can trade Testnet bitcoins on exchanges, here's one: it's mainly an exchange for obscure altcoins, the original announcement is here: https://bitcointalk.org/index.php?topic=5111785.0   
The price hovers around 3€ I've seen trades for a hundred TBTCs   
I'm surprised more hoarders to do not offer more.

[JunkieMiner]

Many websites before launching just launch their testnets, they want to check their website. They also have some allocation for the airdrops, they want users to test their website or their exchanges if they have any problem or issue in their website, they let them tell in the discord or any other form type. So, this didn't have any use as you said, but people can practice through it. For example, if a new user wants to learn trading then he can easily get to the testnet website of any exchange and there he can add liquidity, swap some testnet tokens, and also he can do some borrowing and withdraw tokens there to another place. So, it is better for beginners especially.