Everyone has been in a shower where you can tell when someone flushes a toilet, opens a kitchen tap, etc, as the temperature rapidly changes. There's also other places where the shower is virtually unaffected by anything else.
Is there a way of plumbing in lines (either using a certain size pipe, or certain order of branches) to minimize the sensitivity? Do pro plumbers ever pay attention to this, or do they just do whatever is the shortest run?
In my current house, the shower never changes temperature, despite use of dishwasher, laundry, toilets or other taps. There is a 3/4" line that runs one direction for cold, and another 3/4" line running the opposite direction for hot (the hot water tank is on the exact opposite side of the house from where the cold water comes in). On the cold side, there is the kitchen sink first, and then the bathroom (and I'm 99% sure based on positioning that the shower is first, followed by toilet, then sink). On the hot side, there is a 1/2" line that comes off first for the laundry and downstairs half-bath, and then the bathroom in the same order as before.