EQ Mirror is by far for me the most difficult game.

EQ Mirror is actually my best game (currently lvl 19 and apparently doing better than 94% of users). This might explain why my SPI seems pretty high relative to the amount of games played. For some reason EQ Mirror is included in my daily workout very often. I just keep tweaking until it sounds nearly the same. Don't forget to use the Q setting as well, it's needed sometimes...

Yeah, in all the games, the higher your level the more points you get for each right answer and each level up. I would guess that if you get to level 16 in another game you would get about the same points.

So yeah after looking more closely into the scoring mechanic I was probably under the wrong impression that some exercises were given more weight than others. Looks like it's very much related to the level we are in any game and any other game I would reach level 16 would give equivalent SPI...

One thing to keep in mind is that this is also about gaining balanced skills across all the areas. In my case for some reason initially the compressors games came up most often, so I advanced pretty far there, but I found myself lagging way behind on Filter and Reverb and some others (and I noticed that during my actual mixing). There‘s a setting in the profile that you can set to „smart training“. Once I set this the daily workout started consisting of mostly those games that I was behind on - allowing me to get more balanced - and make progress on all.

I'd say Peak Master as well. As for insight in to the SPI calculation, @Noam Gingold gave details in this discussion last year https://www.soundgym.co/space/talk?id=NASZ2448MAR&t=V24HPBAOJCF

Noam Gingold - Aug 17, 2020
SPI is calculated by the 3 top scores in each game. The first score provides you x3 points, the second score x2, and the third x1. For each game, you will get higher game scores for higher levels, so when you pass levels you will get more points and your SPI will be higher.
When you reach a very high level in a certain game, you will still earn more points for the next level, but the multiplier will be a bit smaller than before. If you continue to pass levels in this game the multiplier will keep getting smaller. At some point, it is wise to focus on reaching high levels on other games to get more SPI.
The multiplier starts getting mildly smaller at level 21, and get a bit smaller with each level that you pass. This way we want to make it harder to get medals (Especially gold & diamond) based on only a few games that you are very good at.