A full day of fishing consists of a 10 hour trip from 6:30 am to 4:30 pm.
Full day of fishing allows you to choose either inshore and/or marlin fishing. Going out for 10 hours allows you to catch more fish.
Predominantly the Marlin waters are a fair distance away, a full days of fishing allows you to get to the fishing grounds and spend more time looking for the Marlin.