From time to time, I see the preposition up appearing alongside a verb or a verb phrase and doesn't add anything to the meaning (or at least, it seems so).
Buckle (up)! We have a long journey ahead of us!
People Snuggle (up) to each other.
Let's finish this (up)
In those sentences, is the particle optional? Because, (to me, at least) they have the same meaning as the verb/verb phrase itself.