What do you think of the concept of waiting X amount of time after ending one relationship before moving on to the next?

I recently broke up with a fairly long-term boyfriend and started dating someone who I had a strong friendship with two days later. The previous relationship was pretty awful for me and I think I had moved on before I even acknowledged it myself, so I did not feel like I needed to wait. But many of my friends are upset with me, or at the very least think it would have been better to wait. For my own happiness, it wouldn't have been, and my ex is fine with the situation. Should I have still waited?