The price of a7-day season ticket is calculated by totalling the cost of 5 return journeys (which most purchasers will actually make) and deducting 16%. The discount given when using a Railcard is 34%. So, as you've realised, individual tickets will be cheaper.
Fare examples (based upon travel between Great Yarmouth and Norwich):
7-day season ticket : £42.60 (equivalent to £8.52 per day if used for only 5 days travel)
Anytime Return ticket (with a Railcard): £6.75