Not always, but it's not uncommon. An entirely smooth succession is pretty rare. The trick is to try and make sure you have a bit of gold for emergency mercs. And also to optimise the primary duchy/county for your main title for levies.

Thanks. And you win by simply outlasting the rebels, I assume.

Also, try and save a sibling or two for the inheritor to marry off to a powerful vassal within the brewing rebellion. Reduces its power or can stop it completely. There are also artifacts that can reduce the short reign penalty. These are very useful when you get them.