Correct product but attention to the number of sheets to be bound

I connected a document of about 150 sheets and one of about 300 sheets.
The binding is perfect for document 300 sheets, the thickness approaches the 30 mm.
In contrast, binding to 150 sheets makes it much less well in terms of both reading comfort than the aspect of coverage.
For effective and clear bindings, I think we should have covers with different sizes and use the most relevant.
Too bad GBC does not offer a coverage mix with different sizes.