Question: I know a lot of posts have been made on this topic, but, I have tried everything. I wanted to move my hot water tank from the first floor of my house to the crawl space. My old unit was performing well, but, the plumber I hired recommended a new unit (mine was 12 years old). Prior to replacement, my hot water worked perfectly!! We could take three showers back to back with no issues at all. Now, with a new unit, I can't even make it through one shower before it gets cold. During the one shower, I constantly turn the hot know to increase the temp until it just gets cold on me. I have taken the following steps:

* Replaced the new HW unit with the same size (38 gallons), number of elements (2), and wattage as the old unit
* Checked the dip tube in the new unit
* Replaced the elements (with genuine factory parts)
* Adjusted the thermostat to 120
* Replaced all the stems in faucets with a one handle (mixing stems).

I have already dropped 1500 dollars on the unit and stems including labor costs. Please advise.

Answer: 
If you increase the diameter of the branch you also increase the time it takes for you to get hot water. In my climate I also like to get ground temperature water so having large branch lines increases the amount of water I have to dump before I get rid of the water in the pipe from the supply entrance to my faucet. This also wastes heat as the branch lines will have hot/cold water and heat or cool the wall spaces - eventually heating or cooling your house. 

I like the manifold arrangement but one quick thing to try would be to just plumb the washing machine into the end of the branch line. I this this would allow the other fixtures to have pressure preference over it. 

The other thing I'd do is eliminate the crazy 90s if you are redoing a section. The plumbing might look neat but you loose significant flow when you make sharp turns. Really the best way is spaghetti with gradual bends.
Personally I would just live with the trunk and branch. It will be very expensive to replumb the house.