Had a question about the length of missions actually. Is it possible to tweak the amount of time for them if needed without failing the mission?

Like to give an example, say someone who has a non-combatant character only needs them away for a few days, so combat testing won't work, but everything else is minimum of at least a week. Or if someone really wants to send their character to kill shift hunters, but only needs the character gone for a week and two would just be too much.

Just mostly wondering if the timeframes are meant to overall be a guideline and not set in stone so much.