Shuffle Play doesn't shuffle correctly

[Heees]

I have a playlist with two of my favourite artists on it and i like to shuffle play them but shuffle doesn't actual shuffle them properly. The ratio of songs between them is about 40/60 so you'd think the artists would play about the same amount of time but it doesn't happen like that. Because the artists are pretty different they don't play with each other. It has to go through at least 12 songs before it changes artists then just sticks to that artist for over half an hour. This is an obvious flaw so please fix it.