Two simple things that helped us with our previous 3 fridge purchases having got another two very wrong. We have moved often over ten+ years.
1/ we have always found for smaller fridges (eg 240l) removing one shelf has always been necessary to get the best balance of use with standard height jars and bottles. It also makes accessing items at the rear of a shelf easier by keeping lower and smaller items at the front.
2/ you need air space around each shelf and the stored items for the cold air to circulate. The right size fridge is one size bigger than you think.
There is no value in filling every cubic centimetre jammed packed till nothing more can fit. Otherwise some stuff gets too cold and freezes and that at the front is slow to cool.
Optionally 3/ the amount of cold stuff you buy and keep in a fridge always increases until you have no more room left regardless of it’s surplus capacity. The more there is in the fridge the more time you spend standing with the door open shuffling stuff around until you can remove or find what it is you need. Perhaps there is some wise advice on how to minimise what you need to keep in a fridge?
Having to fit fridges into a variety of different spaces, generally it has been the outside dimensions that have been most useful. Noting that every fridge has different side, top and rear requirements for air space. These larger than quoted external dimensions are what we have used in a purchase as they are the minimum cabinet space requirements.
Visualising how the internal shelving works is not easy. Perhaps Choice could do as for the washing and drier tests. For these it includes testing with and weighing an optimal and jam packed load for each verses the name plate capacity. For a fridge, have a representative range of different sized items and stack each fridge according to the standard config till jam packed. Score 1. Take at least one of every different item out and continue until the contents have been reduced by one third. Score 2. Subjectively decide how easy it is then to access all the items in each fridge compared to the others of similar nominal volume.
Some fridges may rate better for larger bottles eg champagne, others cans of beer or coke, while some may best suit storage of Coles “ little shop” products and not much more?
While we all use a fridge differently and have varying notions of the right way to stack or store stuff. A standard test load should reasonably compare the effectiveness of the internal space of two fridges with similar quoted volumes? I prefer my sardines after opening kept In the fridge in the original tin with the lid open, if I can assist there?
P.s. there appears to be no consistent correlation between fridge total outside volume, internal capacity (volumetric efficiency), energy efficiency and price. Two similar outside dimensioned fridges could have very different internal volumes as noted. The one with the the greater volume may have thinner higher quality insulation increasing the cost, or just a larger compressor making it more expensive to run. So our current fridge which is deliberately free standing with no constraints was sized on shelf space, then star rating, and best purchase price by brand name/Choice guide. It will not fit many typical fridge spaces. We turned our old fridge space into a pantry and turned down the option of a home beautiful kitchen shoot.