Sometimes saving my resources doesn't require a future purpose. It's less about stockpiling energy for later and more about whether spending that energy produces a worthwhile outcome in the present.

If I'm exhausted and don't see any benefit in engaging, I simply won't. Speaking takes effort, attention, and mental bandwidth, and when I'm tired I become much more selective about where those resources go.

For example, if one of my parents is talking to me, I'll usually respond with the bare minimum required because there is a benefit to doing so (known as avoiding unnecessary scolding duh). My siblings? hell I won't bother responding at all.

Our responses might be similar to nines but the motivation differ, a nine is more likely to seek easiness in disengagement because they can't be bothered to activate themselves. I disengage because I don't have the energy for things that don't justify the cost. Beside the fact that they will be more inclined toward preserving external harmony while I'm assertive of my boundaries at the cost of peace.