The extra item packed for reassurance still takes real space from something else.

Comfort has weight. The just-in-case item may never be used, and it has already displaced something you would have wanted, made the bag heavier on every walk, and increased the effort of every search inside it. Reassurance is a legitimate reason to carry something; it is simply not a free one.

Take one thing out of whatever you carry daily and see whether you miss it within a fortnight. The same reckoning is worth applying to commitments kept for security rather than for use.