Piet

The what-versus-why split is the part that makes this sustainable. I stopped documenting what is installed, because the machine knows that better than I do and my notes go stale within a month.

What I write down is why: why this port, why this service instead of the obvious one, what I tried that did not work. None of that is recoverable from the box and all of it is what I need six months later.

The rebuild drill is the test and it is uncomfortable in a useful way. Pick the least important service, destroy it, bring it back from what you have written. Whatever you had to remember instead of read is the gap.

Six months of everything working is precisely how you end up unable to change anything.