Nonsense! You don't plan according to water pipes but so that you like the floor plan. And you can forget about 3 seconds, 20 seconds are already more realistic. For us, it’s solved like with Basti, guest toilet without circulation and only 4 meters of pipe. There’s no way 3 seconds there. If you have three floors, circulation is mandatory. Leaving it out I would call a planning error, considering comfort requirements!
Planning is not just floor plans. If it takes that long with you despite the very short pipe length, certainly a pipe diameter far too large for a guest bathroom was used,... which logically extends the time until warm water arrives enormously. This is often done because nobody really thinks about it (no proper planning, a large rain shower is rarely installed in a guest bathroom that would require such a diameter...). You can read about the details wonderfully in the pink forum.
That you don’t design your floor plan solely based on water pipes... Yes, you can misunderstand everything however you want
Nonetheless, I expect from an architect that he optimizes the overall concept, not just the floor plan (especially if, as I think some here do, you have certain demands for ecological building). For a nice house there is (at least for me) much more than just a nice floor plan.