Choose the largest Boveda that fits in your instrument case. You can never use “too much” Boveda.
Use more Boveda than the minimum recommended. Think about upping the number of Boveda you use in your case if it’s in an extreme climate (desert-dry or rainforest-like) or when it’s exposed to seasonal humidity swings
Close your case once you remove your instrument. The more you expose Boveda to air, the harder it has to work and the shorter it lasts.