Volume is only the start
A deep cabinet may have high volume but poor retrieval if items sit three rows deep.
Shelf spacing matters
Usable shelf heights often matter more than total cabinet height.
Container shape matters
Rectangular bins use space differently from baskets and irregular objects.
Access has value
Some empty space can improve usability more than maximum packing density.
Practical boundary. Measure first, respect product load limits, and do not improvise wall, ceiling or overhead installations when the structure or appropriate hardware is uncertain.