Let’s assume that it takes about 15 minutes (rounded up to 1,000 seconds) to assemble a single iPhone. How many parallel production pipes need to accumulate ten phones a second?
This is not how manufacturing works. Let’s say it takes 1000 seconds to assemble one phone. The assembly line may have 50 steps. If so, at any given moment there are 50 phones in process. When you first start production it takes 15 mins to get your first phone and then after that every 20 seconds a completed phone comes off the end of the line. In this scenario you need 200 of these production lines to generate 10 phones a second.