To view some thing it needs to be above 1400 and to reach some thing needs to be under 1400 so a thermostat which requires both is often put so centre line is at 1400 mm.
However some one in a wheel chair can't stand up to view some thing, but an able bodied person can bend down, so eye level in a wheel chair is around 1200 mm. Things like oven knobs often need viewing from above, same with some thermostats, so around 1000 mm is a good compromise so wheel chair users can view from above.
Sockets for a wheel chair user likely 300 mm is a good height, but in non domestic the building regulations say 400 mm, I have often wondered why domestic 450 mm, the centre of a wheel chair wheel is around the 300 mm so that is often the widest point of the chair, so in a wheel chair users house you often see damage at that height, so 400 mm raises the socket above the height where damage is likely.
In real terms it is unlikely that wheel chairs will be used upstairs, so upstairs the most like item to damage a socket is the bed and the vacuum cleaner, so sockets at the bed head should be around 250 mm to top or a little less, but over 100 mm so clear of vacuum cleaner, the regulations say that we should consider any damage likely, and I in error set the bedroom sockets low, the floor finished level was above what I had expected, and the LABC inspector accepted that upstairs sockets were low to prevent damage from bed head, that was not the real reason they were low, but I got away with it.
As said for a new build heights are given, but they are flexible, so I put light switches at 1000 mm in mothers house as she was in a wheel chair. Also there are rules about corners, again as wheel chair user can't assess a corner. But in your own house do as you want.