Skill acquisition requires frequent practice. Studying one day per week is far from enough for the purpose of building up long-term memory. It is the same with learning to sports or to play the piano. You can’t be a good piano player just by practicing once a week. If you are serious about English learning, you can always find the time. Studying 30 minutes per day and 4 days per week is much more effective than studying 2 hours at one time once a week.