Another way of looking at compression power is in terms of space savings, defined as
space savings = (1 - encoded size / uncompressed size) x 100%For example, a codec with a compression power of 2 results in 50% space savings. From the point of view of space savings, a compression power of 4, corresponding to 75% space savings, is only 50% better than a power of 2. In fact, to save twice as much space as a 50% space savings, you'd have to save 100%, which corresponds to infinite compression! Clearly, incremental improvements in compression power yield diminishing returns in terms of space savings.
For a concrete example, each hour of D1 video (uncompressed standard-definition video in Y'CBCR 4:2:2 format) costs you 70 GB. Encoded in SheerVideo format, it only costs you 30 GB per hour, saving you 40 GB per hour, or nearly 60%.
Here's the same line-up of perfectly-fidelity QuickTime codecs, showing a comparison of space savings instead of power: