yeah, I've been getting used to being careful in parking, and having a little reverse on flat land helps (I live above Boulder a few k ft -- not much flat here)
I've opened up 2 transmissions before on my saturn, once for a core going to the yard anyways to see how it went together and give it less "magic"
the 2nd was replacing a single nut that was prone to going loose and causing issues -- tend to find with mechanics that the trick for me is going very slow and documenting everything (pictures, labels, and baggies) then triple checking each section frequently with a torque wrench
but I try not to start anything until I have an understanding of the full process involved in tear down and put together, including having any part I "Might" need on hand before turning the first bolt for anything more complex than swapping an alternator or other easy to reach part
in the middle of a motor swap on a 4runner (from 2nd to 3rd gen) so not gonna tear into my legacy anytime real soon, so lots of time to gather insights, documents and parts
appreciate the concern though, when I was younger I got myself into trouble a couple times tearing into motors without knowing what I was doing and having to scrap them as a result
good lessons upon reflection -- better to learn from others mistakes