Bromine tubs benefit just as much from shocking as chlorine tubs, even when the residual is in band. Here is why, and the routine that takes 20 minutes.
A bromine reading in band tells you that there is enough free bromine in the water. It does not tell you how much organic load has built up or whether bromamines are starting to form. Weekly shocking in a bromine tub is just as important as in a chlorine tub, and it takes the same 20 minutes.
Non-chlorine shock has a bonus role in bromine systems: it converts spent bromide back into active bromine. A weekly shock effectively refreshes your bromine reservoir on top of clearing organic load.
Without the weekly shock, the bromide level rises (you keep adding bromide, never converting it back), the water starts to feel slick, and the tablet feeder stops being able to keep up.
Pick a regular day, ideally an evening. Dose a full bottle dose of non-chlorine shock per the per-litre rate.
Lift the cover and run the jets for 15 minutes.
Replace the cover and walk away. By morning, free bromine should have climbed slightly and the water should feel fresh.
Once a month, or after a really heavy session, a chlorine shock at 10 ppm reactivates the bromide pool more aggressively than non-chlorine shock and gives a deep clean. Wait until free chlorine is below 3 ppm before bathing.
Do not switch the routine permanently to chlorine shock. The CYA in some chlorine shock products is wasted in a bromine tub and can build up TDS unnecessarily.
Unscented sodium hypochlorite (the same active as household bleach but in pool grade) is a clean chlorine shock for bromine tubs because it adds no CYA.
It will spike for a few hours, especially after a chlorine shock. Wait until it falls back to 4 to 6 ppm before bathing. The high reading is not harmful to the tub, just to comfort.
No, the shock activates existing bromide. Adding more tablets at the same time is redundant and overshoots the level for days.