Decades ago when I was doing electrician stuff (apprentice, passed the journeyman's test but not sure I ever filled out the paperwork) in MO code was 12 AWG and 15-A outlets. Fast forward a few decades and I discovered -- far, far too late -- that in CO then code was 14 AWG and 15-A outlets everywhere. Kitchen outlets same as others, but there was a special requirement that you had to have an outlet every 2'~3' or something like that. If I had known I would have specified 12 AWG wire everywhere but didn't think about it until walking through the house after the wires were run...
When we finished our basement I added three 20-A outlets in the media room to get 12 AWG wire, and a fourth in our "exercise" room for a treadmill. Talking to the electrician, he said it was a mess around the area. We live in the northern part of our county, outside city limits, and there were slightly different requirements in the city a couple of miles away, another set for the county a mile north, and in the big city just (20 miles) south of us.
Bottom line is code varies by state and in some cases by county or municipality. If you are having work done, or building or remodeling a house, check with your electrician for the codes that apply and what you might want to change. In our case there would have been no problem running everything with 12 AWG (higher cost, natch) to 15-A outlets, providing margin for later if desired.
Ditto plumbing... The house was fully plumbed when a local friend said "I hope you went with 3/4" pipe to reduce loss since you're on a well." Nope, never even thought of it, so 1/2" everywhere. Too late to change. Impossible to be an expert on everything...