1,878,000 dishes of food.
Based on the fixed sales rate of up to 30 dishes per minute, it would take me approximately 43.5 consecutive days of neither cooking food nor accepting gifts before I sell all my current dishes:
Dishes sold per day = (30 dishes/min)*(60 min/hr)*(24 hr/day) = 43200 dishes/day
Unless you exclusively cook a short list of foods with long cooktimes every day, you'll almost always end up producing more dishes than you sell each day, given that you don't have excessive downtime. Thus, the types of food I'm serving might change as I cook different foods, but my current 1,878,000 dish total will only increase as I accumulate more dishes each day.
Because of the fixed sales rate, I will have at least 1,878,000 dishes sitting in my restaurant and never be sold. If you look at dishes as an investment (i.e., you put in time and coins and get XP and coin profit), the 30 dishes per minute sales rate bottleneck keeps many dishes (1,878,000 dishes for me) from becoming coins and pretty much keeps you from ever receiving the returns on your investments.
Additionally, the fixed sales rate also restricts the profit of your restaurant. Calculating the profit per hour -- the difference between the gain per hour for my restaurant and the cost per hour of cooking a given food -- 14% of the foods make you lose money and many others give you marginal profit.
Gain per hour for my restaurant = (Average price per item of my 12 foods)*(30 dishes/min)*(60 min/hr) = 4985 coins/hr
Cost per hour of cooking a food = (Cost of dish)*(number of appliances)/(minutes to cook food)*(60 min/hr)
Personally, I lose money every day, and I am forced to go out of my way to cook long food items to gain any money. I've pretty much been unable to expand for the past 40 levels because I have millions of dollars worth of food tied up by the limited sales rate. I know that some people struggle to keep food on their counters and others like to stockpile their restaurant with all sorts of food, but in both cases, people have control over their dishes (e.g., having the option to close your restaurant by blocking the door with a chair).
Does anyone know if Team Lava is open to providing some means to increase your sales rate (e.g., purchase more host tables to draw more customers)? Raising the sales rate's ceiling would work, too.