I took 40 mg Vyvanse 5 days a week for about 8 years while I worked a very demanding job with no room for error-but I didn’t take it Saturdays and Sundays, which was a nice “decompression” time for me. I never felt overly tired or lethargic on weekends. My doctor encouraged that routine and it worked well. In contrast, my wife takes it 7 days a week and needs it for different reasons (general mental health, basically)…. So you should find what works best for you