There is more than one chemical marketed as bleach.
Traditionally, “bleach” usually meant a weak solution of sodium hypochlorite or a related chemical. In water, hypochlorite partially forms hypochlorous acid, which is a powerful oxidizing agent, and does the disinfection.
These days, although sodium hypochlorite is still available, many bleaches use a weak hydrogen peroxide solution as the active ingredient, marketing it as oxygen bleach (instead of chlorine bleach), environmentally friendly bleach, or colour fast/fabric safe bleach.
There are others, but these are the most common ones. There are a couple of reasons that usage instructions may be a bit vague. These chemicals work because they are highly reactive, which and they are rapidly consumed in the process. The amount of disinfectant required depends on how much there is for it to react with, so it’s always best to remove as many contaminants by rinsing, for example, before disinfection. Also, disinfection byproducts can be unpleasant. Foer example, the “chlorine” smell that people associate with indoor swimming pools is actually chloramine, formed by oxidation of ammonia by hypochlorous acid, and there is a lot of effort put into preventing organic matter getting into municipal water tanks not just because of the added cost of the extra disinfectant, but because carcinogenic trihalomethanes can be formed as a result of the disinfection process.
The other reason that usage instructions are a bit vague is that both sodium hypochlorite and hydrogen peroxide are unstable, meaning that they degrade over time. The rate of degradation varies with storage conditions such as temperature. The manufacturer doesn’t know how long you’ve had your bottle of bleach, or how you’ve stored it, so they don’t really know either the strength of the solution in your bottle or the level of reactive contaminants on the item you want to sterilize, making it a difficult job to provide one size fits all general guidance. Most of the liquid is just water, so when you use it, you can’t really tell if there is surplus active agent, or if it’s been completely depleted.
I would use a hydrogen peroxide based bleach rather than a hypochlorite based one for articles that people touch, because hydrogen peroxide breaks down into water and oxygen.
I don’t know exactly what you are sterilizing, but perhaps the manufacturer can provide some advice. Heat and UV radiation can also be effective in the right application, so it may be that boiling water or drying in the sun is a viable alternative. There may not even be any need for supplementary sterilisation beyond drying if the equipment is only used in chlorinated water.