I believe that if you should not spend time making or preparing food. I think you should take that time and either spend it doing the things you enjoy away from the shop or spend it developing more coffee business.
My largest profit margins are on espresso based drinks. In a perfect world all of my customers would come in and only drink espresso based drinks. Any money I spend on food equipment could have been spent better trying to get an espresso customer to come in everyday.
So, I would rather spend an hour a day trying to get a latte drinker than spend an hour a day preparing the food, storing the food, purchasing the food and hoping that when they buy that food, they also buy and espresso based drink. Then proceed to watch my margins fall while I work more hours at the shop.
Beside the fact that I have a coffee shop. Want coffee? come to me and I will make you the best coffee drink you can get. Want lunch? go to [insert in your local restaraunt that you have relationship with] and buy a latte for the trip.
What I call Grab-n-go food I will have on my counter but I do not spend time preparing or selling any food at all-waste of time and money.