Precautions for mixing pools
1. Don't mix the pool, if you are crooked and there is no original stone, you will go home empty-handed, ready to draw 180, at least 160 to be sure. 2. The mixed pool is good: the character pool has some wants, and if you want to bet on 2up characters, you don't want to test the water with a small guarantee, and you can directly seek stability with 160-180 shots, and the characters want to do so. 
For example, this time Eula 0+1, the math expectation is a little higher than Eula's previous up draw 0+1, which is good for the role chef.
The mixed pool is to set the track once, 50% of the ** (role) you choose will be drawn, and the other** (role) will be equally divided by 50%, and you will be guaranteed to get a five-star character by 90 if you set the track. 
If it's crooked, then draw up to 90 to get the up item you want. The track is not inherited, in other words, that is, this pool is not inherited, if it is crooked, it will not continue to be drawn, and it may be crooked next time, and you will lose if you are crooked this time.
A Wave of Liyue Mixed Pool (6 characters, 11).
Characters: Keqing, Seven.
Seven, Childe, Walnut, Ganyu, Yelan.
Xiao is too close, Shenhe and Baizhu are not enough)
*: Blade of the Blade, Rock Green, Sword of Nothingness, Staff of Goma, Lance of Rainbow, Calamity, Kite of the Harmony, Earthly Lock, White Star of the Winter Pole, Ruoshui, Bow of Amos.
With more and more extractable characters, there is bound to be a problem that the desired characters cannot be reproduced.
FGO takes a lucky bag every year, which is very unstable. But because FGO is not much of a reproduction compared to other games, the character sea view room was commonplace a few years before the game was launched, so everyone accepted it.
Genshin Impact's efficiency in launching new characters is not fast, but it's also approaching a critical point. I'm glad that the authorities have chosen such a gentle approach to address this problem, benefiting some players and not infringing on the interests of most players. 
There are also drawbacks, the mixed pool and up are equivalent to three pools at the same time, and it will be difficult to top if you want both.