I'm.... not convinced about that skill trainer. I found him, I set it up to loop on him, and left it for most of the afternoon. Got up to something like 18 strength and I don't think I'm doing any more damage to rocks than I was when I started (I say something like 18 because I don't remember, but by the time I broke the white rock I'd looped enough times more that my strength was 21). I'm not even sure I'm doing AS MUCH damage as when I started. But each full action bar adds maybe two pixels to the progress bar.
I also have no idea what the different impacts of strength vs "today" strength are - but "today" strength always starts out at 0 - not sure if they're supposed to be added together, or how I'm supposed to understand those stats.
And, if I'm being honest, the looping mechanic doesn't really seem to add anything to the game. It just makes it have to repeat the same thing over and over and over again, which granted is kind of the definition of idle games - a repeating game loop. But the "time loop" mechanic (which isn't really even a time loop for the most part - even the tips largely dismiss it by describing it as simply "not remembering" the previous day... which is funny given that you exactly repeat the previous day - except where you've actually made changes that aren't reset.. but I digress) doesn't even provide that "numbers go up" psychological reward loop/dopamine hit that idle games normally would. You just pick the next rockyou want to beat on, and then watch the same loop happen over and over like 100 times until the rock is smashed. I think it's an interesting mechanic, I'm just not sure this gameplay loop realizes its potential.