Linguist here. In one sense yes, but there are many other senses, also maybe in one language the cases are regular but in the other they aren't. There is complexity from phonetics/phonology to pragmatics, and all languages distribute it differently. Basque cases for example are very regular, like Turkish or Hungarian, but Russian or Icelandic cases are less regular. So it's actually easier to pick up Basque at least the morphology than it is to pick up Russian or Icelandic.