Should I buy the 18+ Student Oyster photocard, if I travel only 10 times weekly and within only Zone 1?

I already read the official website for the 18+ Student Oyster photocard, but am still overcome by all the new details and complication. Based on the following, should I buy the photocard? Or is it cheaper to continue using Oyster and pay as I go?

I am a student within Zone 1 in London for the next 4 years. Thus:

1. Minimum weekly travel: I will bus at least 10 times weekly, twice daily for 5 days, from my residence to campus.
2. Maximum weekly travel: I will bus at least 20 times weekly, 2x for 5 days, because I lack time to go out more than 2x day.
3. I will travel only within Zone 1. (I lack time to go anywhere beyond!)
4. I will do the above from Sept. to June every year, except for my total vacation time of 1.5 months (Christmas and Spring) + 3 months (Summer) when I will return home.