It took me a few years (because I'm VERY type A) to not get so stressed about each cake.
I used to have to start everything on Monday and the process would go on all week. Mainly, my goal was to have the wedding done by Thurs or Friday so that if anything happened I still had time to rip the whole thing apart and re-do.
There has been a transition time where while I waited to work on the cakes until later in the week, I still stressed about them all week until i could get them going. I would think about everything I had to do, and the thinking was WAY harder than the doing!
Now this summer busy season, I am teaching myself that things WILL get done, that I DO know how to fix issues, that I need to enjoy the pre-planning and anticipation as well as the down time. I used to feel guilty when I didn't work on a bride's cake all week, like I was letting her down!
Another thought is to find where your passion actually lays. I am a hardcore wedding cake gal. Nothing thrills me more. I do NOT like putting in as much time if not more time on little Johnny's first bday cake. It's just not my passion. This week I only have 2 weddings and no celebration cakes (although one wedding has 11 cakes in it!), and I couldn't be less stressed. I've gone shopping, out to dinner, taken a nap (gasp!) And that is because I'm calm and inside my passion and confidence.
YOu mentioned another post where the OP was having a hard time with ping-pong emails and the lessons she was learning. She is one of the most amazing decorators I know, and a good business woman too. But she chose to do everything custom and not have standard prices. Because of this, she also chose ping-pong emails. I have learned that if I am simple with my pricing I don't have a lot of ping pongers. So you need to decide what works for you in your pricing structure too.
Ok, another novel out to bed