Track pads are truly difficult! I've only ever used them a handful of times unfortunately so I'm not sure if I have too many tips but hopefully these help!
I think the main struggle with trackpads may be wearing out the energy to do that much detail? I think blending mixed with larger patches of color like seen
here may help, with texture only being on the sides. You could even get away with less texture by blending some bits in and the farther away it gets the less texture you have to put in. Alternatively you could see if layering scribbles helps, different pen sizes etc.
With rocks it's mostly to break up any large smooth blank space on them as I layer it he colors. Rock looking too smooth? Add a slightly darker/lighter color than the color that area is and put more breaks in the surface.
The techniques here that I was using was a lot of layering and getting colors to nicely transition into each other without blending, but I use blending more in most of my serious backgrounds to create less work in layering and get them to be able to be contrasted against any characters or bases that have clean line work.
Most importantly if you're doing a piece, do not make yourself do what's behind the character/s you're adding to the piece, it's not worth the effort to put work where no one will see it. Can't get away with that for species bases though.
And ofc practice over and over again anything you're not confident with!