A weekly study programme can be very useful_____.
A)after good study habits have been established
(The study program may be prepared to establish good study habits.)
B)but doesn't lead to better study habits
(It should've been 'it doesn't' or directly 'cannot').
C)so long as it isn't very detailed
('detailed' is a positive adjective, if it was 'complicated' instead, we could conveniently go for this.)
D)even if one doesn't keep to it exactly
E)If one knows it can't be changed
(A study program can be easily changed.)