What people buy differs according to time of day

I know it’s stating the obvious. By maybe there’s an insight here for retailers? I’ve been standing in grocery stores trying to catch people browsing my client’s product. I’ve noticed that there are very specific time slots when people buy their product – for example, in the morning before lunch. There are times too when they’re not buying because they’re going to another part of the store – and if my client’s product was in that part of the store, and positioned with those types of products it would do better at that time of day…

Should grocery stores be changing their stock around depending on the time of day? Should shops have morning, lunch and evening ranges? Stupid thought? Or not?