What is crucial for travelers to check before departure?

Confirming all travel reservations and requirements in the Defense Travel System (DTS) is essential for travelers before departure because it ensures that everything is in place for a smooth journey. This includes verifying flight itineraries, hotel accommodations, transportation arrangements, and any necessary approvals or travel flags that might affect the trip. By doing this, travelers can avoid potential issues like missed flights, lack of accommodation, or unapproved travel that could lead to disruptions in their plans.

While reviewing a budget for travel expenses is important for financial planning, it does not directly impact the logistics of the trip. Similarly, updating personal contact information is useful for maintaining accurate records, but it doesn't impact the travel itself at the moment of departure. Submitting a final travel report is necessary for accountability after the trip, but it does not address the preparations needed before leaving. Hence, confirming reservations and requirements is the most crucial action for ensuring a successful travel experience.