Yeah that's because you've got pretty much the perfect setup, not because THAT specific kind of shot is easier in general lol.
Still much easier to hit the red circle with a 3s nade, and this is the important part, precisely!
I highly doubt you could for example, OPEN that right side of the tree, with a bounce back with as much precision as you could a 3s shot.
But, when it comes down to it! Doesn't matter what shots are generally more challenging on average, it all comes down to your personal skillset and beliefs.
If you actually believe it's easier or harder for yourself, then it probably is for you alone lol.
"Not doing maths, not going for visual aids, don't posses knowledge of sprites behaviour/aim reticules etc.. "
Also, unless you're playing with a blindfold on, everyone with eyes uses visual aids.
And if you ain't doing math, then how do you decide the fuse and the timing?