Elle,
Once a week does not sound too often for the amount your tub is getting used. I sometimes shock twice in one week with extreme use. It is normal for bromine readings go high when shocking, that's part of the shock process. One clue that your water needs shock is when it starts to smell "chemically".
One thing to consider is the amount of shock you use. If I recall correctly the user manual recommended 4 ounces of MPS a week for the Euphoria. I personally found that to be very excessive, I now typically use 1.5 ounces when shocking.
Ultimately as windsurfdog already said "If your water has been perfect, don't change a thing."