We have a limit on how much ratio we can fit on a particular rocker length and offset. We keep a nominal amount of material around that adjuster to be sure that the rocker lasts a very long time. In most cases the amount of offset the adjuster screw has is the biggest limiting factor. A rocker arm with zero offset is far more likely to be able to accept a high ratio then the same length body with a lot of offset.
The way we can fit a higher ratio in a rocker is building a rocker set that has a longer fulcrum length or in some cases going to a steel rocker option. With steel being stronger, the amount of material around the adjuster can be less. All factors are considered when selecting the correct rocker assembly and options for your combination.