Not automatically, but heavy-duty applications usually leave less room for performance compromise.
As bag size increases, the total load, film area, and number of potential weak points increase. Natural-fiber content may need to be adjusted to maintain toughness, elongation, seal strength, and puncture resistance.
The correct approach would be to test several formulations rather than setting a marketing-driven fiber target in advance.
For example, a small liner, a 13-gallon kitchen bag, and a 39-gallon outdoor bag may all use the same material platform but have different formulations.
A platform should allow application-specific optimization rather than forcing every product to use the same percentage.