Have you mesured the inside of the shoe before assuming this particular model fit .5 size bigger than another ?
I can tell you they are true to size , on my 13.5 i 've mesured almost 315mm inside , perfect match with the box label 31.5cm .
Some shoe runs larger than others but generally the last is the correct size , and that's what true to size mean .
I bet a lot of people doesn't even know their foot lenght / true size .
For example my foot lenght is 304 mm , my optimum shoe size inner lenght is 314 mm , that's why i go with 13.5 .
I could go with a 13 but man my dogs will feel the pain after a few hours , 6 mm is not enough .