Standing water in the pipes when you turn it on is often lukewarm, or "luke-cold" and then it gets colder. In this case you need to adjust the temperature along the way, unless you are happy with the cooler temperature. To add to this, I've got a doozy of a reason to like single handle faucets. In some places, cold water is Very Cold. You want to mix it. E.g. Lake Ontario water in Rochester and Toronto. A single handle lets you temperature adjust with one hand, or even with a finger or a bump. Plus you can adjust total flow at the same time. In some places, cold water is Very Cold, in Winter... but not real cold, in Summer!! You want to be able to mix it easily, season to season! E.g. downstream of Lake Ontario on the St. Lawrence river, which has freezing cold water from November to March and not cold from late Spring to early Fall. Parts of upstate NY, eastern Ontario and Quebec. With seasonal variations in cold water temperature you want to mix it easily, and the requirement to mix it changes from month to month. You heard it here first. So, in some regions, it really comes down to temperature. This IS a functional reason to take single handle faucets and not two handle faucets, which force you to toggle back and forth across two handles on opposite sides of your body. You read it here first. .

I appreciate the response. We have a full clear view of the entire pipe work - full size basement unfinished, so it is not as bad as most people who have to deal with croll space. The lines all run through joists but none are insulated - the lines are just below the insulation. The main lines are 3/4 PEX that drop down to 1/2 PEX for each fixture. They are all on the same level/height. The kitchen is very close to heater - utility room is next to kitchen. The MB is in the furthest opposite end of the rancher. Just take MB in consideration -- it has three different fixtures - two sinks, one bath tub, and a separate shower stall. The tub gets hot water the fastest - almost in 20-30 seconds. I don't mind the wait for shower so much - it is to be expected with on-demand heater. The most irritating problem is that it does not hold temperature through a short shower. I wonder if the sensors in kitchen and shower fixture are worn out -- they get the most usage. All fixtures are original to the house - which was brand new built - 5 year old.

I use jelly rolls (cookie sheets with a lip around) two or three times a week to roast vegies and such. The only way to clean these is to soak it in the large single sink while we are eating dinner and wash by hand. They are too big for the DW. I also use many large pots and pans that do not fit or can go in the DW, ie LeCrueset. These often need to be soaked. I would NOT want to soak these on the countertop. Just my thing. So even if you wanted to have a double sink, I would make sure that there is at least one sink that you can soak your pots and pans that you use regularly. I think double sinks that are divided to have one large and one tiny can be a reasonable compromise, especially if yo use the disposal quite a bit AND you do not have a separate prep sink. I do not use the disposal. I put everything in the compost. So this is not a necessity for me. I have never washed dishes by "soaking" the dishes in water. I just turn the water on and off as I need it. For example, I squirt the soap on the sponge, scrub what I need to wash, then turn on the water and rinse. For this reason, one handle faucet is a must for me. I could NOT use two handled faucets. They are too disfunctional for the way I do the dishes. I tried the dishpan for a few days. I did not know how I would store the darn thing. (storing it in the sink defeated the purpose of having a large sink!) I tossed it. If I ever need to soak something, I fill a large pot that is dirty (or just get it out) and put other smaller things in there. This is a rare event. I think you have to figure out how you work and create the equipment that works best for you.

I just got a new ruvati stainless steel sink in a 60/40 split. It took me forever to decide because I felt I had to get a large single bowl. I finally chose what I felt I would like the most and I love it. I've had it three weeks and am so happy with it. I have two friends that each redid their kitchens and got single bowls and regret it so not everyone dislikes the double bowl sink. I'd never want a 50-50 double but the 60-40 meets.all my needs.