Not sure what you're missing, but I'm a fairly new hot tub owner using bromine as well. Still trying to get this chemical treatment thing under control myself. I use a Taylor chem test kit (highly recommend getting one); they are way better than the test strips.
1. Try adding the shock in on a day where you know you won't be using it for a couple of days.
2. I'm told by a guy that does pool/spa maintenance as a side business that you shouldn't need to shock your spa at all if you are keeping all of your chemical levels where they need to be.
3. Something I've tried and seemed to work well, was I was throwing in a small dose of non-chlorine shock after each use (we use ours about 2 times a week) rather than a weekly full treatment. My water stayed clear and levels seems to be good, but I still have to add a little bit of bromine granules once a week or so and I use a bromine floater (which doesn't seem to work very well for me).
I use a bromine floater and find that it seems like the bromine levels go to basically zero after a few days of no use and no other treatment. I was away for 4 days this past weekend, before I left water was clear and levels good. I come back to cloudy water, low pH low Alk and basically no bromine. I treated it and got the pH and Alk where they should be. Added bromine granules to get bromine levels to 2-4ppm. Water still cloudy, but slightly improved. I just shocked it... I use Leisure Time non-chlorine shock (Renew)... of course now the bromine levels are way high.
I think my mistake was that I added bromine granules yesterday, and today I shocked it... so the shock "wakes" up the bromine and now it's way high... This is the second time this has happened to me now that I've returned from a trip... I'll monitor the bromine levels and either wait for them to come back down over the next couple of days or just drain out some of the water and add fresh water back in to bring the levels back down if it's not where i need it by the weekend.
