Having worked closely with a Mcdonald's franchisee for some time, I'm pretty sure your observations are merely anecdotal. If you look at Mcdonald's revenues by average franchise, and adjust for number of hours served, breakfast & dinner revenues are roughly equal (in the simplest case just measuring rush hour breakfast revenues of 7-9am with rush hour dinner revenues of 5:30-7:30pm).

I'm willing to be wrong on this. It's based on my observations in a few different cities I've lived in.

Were those observations mostly done while you were driving home hungry?

I was driving towards a CBD one day low on fuel and noticing that all the petrol stations were on the other side of the road.

After that, I noticed it everywhere I went.

Anecdotally the petrol station thing aligns with my experience, and my preference for filling up on the way home.

Slightly different situation for Mcdonalds though - they're trying to market convenient, fast breakfast food to morning commuters. If the location is most convenient to city-bound traffic, I think it would have a bigger positive impact on morning revenue than the corresponding negative impact on evening revenue. People are in a hurry in the morning!