100% correct. There are no shortcuts either.One problem is that sometimes the vocal rhythm and the bass rhythm don't always match up. This makes you try to split your attention, which usually doesn't work very well.
Hints to make it work? Start slow and work at it. The best situation is when you know either the vocal or bass part so well that you can go on automatic pilot and not think about it. You can then keep your attention on only one thing.