I've just started playing Crusader Kings 2. You probably get questions about it all the time, but if not, the basic premise is that you play as a fuedal dynasty during the Middle Ages.

As one character dies, their lands are inherited by one (or more, depending) heirs. For a lot of Europe, the default is Gavelkind succession.

My question is how accurate to reality would something like Gavelkind (all land split between the sons) have been. From my very limited reading, I know the name Gavelkind relates to a very specific group of people, but it appears the practice was more widespread throughout Germanic tribes (even if it had different names).

I know Charlemagne split his Empire between his sons, and Charles V of the Habsburg had his Empire split between his brother and son, but was this dictated by any type of law /tradition (like Gavelkind), or was it just something they wanted?

Did laws even exist within realms that dictated how fuedal Lords had their lands inherited, or was there a degree of freedom?