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They actually do:

Depending on the temperature and humidity at the altitude the contrails form, they may be visible for only a few seconds or minutes, or may persist for hours and spread to be several miles wide, eventually resembling natural cirrus or altocumulus clouds.

As far as "horizon to horizon" is concerned - that's about 350km for a plane flying at an altitude of 9km (FL300, cruising altitude for long-range flights.) The photo only shows a part of the sky (and some trails actually have turns in them.) On large continents (e.g. America or Central Asia) or over the ocean (if the photo is taken near a coast) it's perfectly sensible for a plane to fly 350km in a straight line.

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