To be honest, I don't wait an entire day usually, but it does heed the best results. The primers dry really fast and they are base coats anyway, so I would say give them a few hours (maybe 3-4) between coats. The main thing that takes a while is going to be clear coat. If you don't give it a while to dry you'll notice it is "soft" and sticky. You may reassemble it and find that when you flip it open the clear coat wasn't dry and it pulls a little paint off of the lid (I've done it, it sucks).