[psunavy03]

This is US Navy-specific, and the person you are replying to seems to have a dated experience of when beer days are authorized. It's every 45 days underway without a port call in sight, and this is governed by formal published regulations. Most ships pull into port at least every 30-40 days outside of major combat.

Ground troops in Iraq and Afghanistan in the Global War on Terror were under General Order #1, which prohibited alcohol in theater, but elsewhere like Djibouti and Qatar were authorized three beers a day maximum.