Endure Elements lasts 24hrs.
Why would you need to have more?
Because the first one somehow gets dispelled. It does tell you the caster level, which in this case would only be needed when someone tries to dispel it.
And because, as a touch spell, it can be cast on others. Was the intent of the Survivalist archetype really to give the entire party the effects of Endure Elements (which it does, if the spell-like ability is useable at will.)