Schematics for running new water supply lines

I have a very simple house, 1000 sq.ft. Water heater is going right behind the tub so I'm assuming that we'll not have to wait long for hot water for showers. I did some reading and spoke to a plumber friend about running new lines and came up with the attached pic. Basically just pulling all the 1/2" runs off the 3/4" line and keeping it 3/4" until I get to the last fixture on the line. Should I be concerned with loss of pressure when someone flushes a toilet?

thanks!

Wow... I totally dont understand that drawing...lol To answer your question, yes what the plumber friend told you will be fine. Run a 3/4 trunk line for hot and cold and pull off 1/2 to feed each fixture. at end of line use 1/2 to feed last fixture. no worries.
Here's an easy rule of thumb 1/2 inch line feeds 1 or 2 fixtures 3/4 line feeds 3 or 4 or more.

I was wondering if it would only makes sense to me. It's a bit cluttered, but it will help me figure out what fittings I need and is just as you described.

So you don't think I'll have any issue with pressure when showering and someone flushes or turns on the washer?

nope. it will work fine. My own personal house is a 4 bath with 3/4 trunks running throughout and 1/2 lines pulled off the trunks to each fixture. 3/4 main line from the meter at the street (also hot water recirculation). I wouldnt tell you to do something that i wouldnt do in my own home. BTW, as a new construction plumber ive plumbed thousands of new homes. the biggest being 7.5 bath 2 kitchens 2 laundry rooms. it has 1inch main from street 3/4 trunks.. 1/2 pulled off trunks to each fixture ( it also has circulation which means the house is piped in series which makes it even more difficult to control pressure drop issues) It works perfectly.
No worries. I promise. Now about those drawing skills......lol

Good stuff. Yeah let's hope my plumbing skills are better than my drawing skills. At least I used different colors.