It really depends on the organization: the Holy Grail is to have a well developed Sales Support function that prepares decks for sales people from a data source which is pre-approved (some investment banks have that, it's awesome) so that the Sales people can focus 100% on doing their thing.

In smaller, scrappier companies or just in less "sexy" industries, sales people are known to prepare their own decks and whether prior approval is sought is really to the mercy of the individual's integrity and savvy.