Sometimes I mix the mysteries of the rosary and meditate on different parts of Jesus’ life, not necessarily on the prescribed day. I never thought about it until someone said it was disrespectful. Does the rosary have to be said in a certain way to be effective?
When you are praying the rosary privately, you can mix and match. The object of the rosary is prayer. If you want to pray five decades, meditating on one mystery, it’s fine. There is absolutely nothing disrespectful in this.