Have to say, they've been eye-opening for me (as an electrical engineer!) - partly very useful to monitor device draw throughout the day and partly to monitor/control 'sets' of devices (eg all TV units, all NAS' and so on). Lots of devices are fairly poor in their draw/power management and being able to schedule them is handy.
Being a purist, some devices are amazing how they just mindlessly ping/power cycle cloud servers - so being able to spot the draw patterns and schedule them to just turn off from midnight to 6am to save this is handy.
At the very least, I'm just a data nerd and it's cool......
I have an unraid server I can login to from anywhere now and just turn it off if need be remotely.
I also have smart plugs that do the same for the subwoofer in my 5.1 set up.
Everything else I'm happy being on standby tbh. Having to explain to the wife she has to turn stuff on using an app before using it would be annoying and tbh it's not a lot of stuff using lots of power.
The main power hungry items are usually stuff which heats air or water. So kettles, showers, hair dryers, tumble dryers, fridges if you live with someone who likes to open the door and look at every item before picking up one then leaving the door open to put it down on the worktop before going back for a second item, etc.
I turn every plug off in my kitchen every day bar the main appliances like fridge, oven, dishwasher. Everything else gets turned off including the microwave. Why because it's easy to do as it's right there in front of you and your normally up on your feet when using it.
However TV's never get turned off at the switch, neither does the avr, multiple ethernet switches, access points, soundbars, PC, etc. Too much hassle.
Tbh I couldn't even power down anything as I have so much smart home stuff I need all the ethernet switches and access points on like for cloud recording the doorbell. Access to CCTV, smart bulbs, etc.
So I have two groups. Stuff which gets turned off and others that are just left on. Having a schedule has worked for me in the past for grow lights but other than that there is nothing I can put on a schedule.
The problem with turning off my unraid server remotely is I need to be physically there to turn it back on using the power button on the pc case.
I've never really looked into power on by ethernet but I suppose I could and that's essentially the only thing I can realistically turn off which would actually save a useful amount of money and be worthwhile.
Most products these days use bugger all especially in standby.
Also I have solar panels if I don't use the power it gets given away so technically makes zero difference to the pocket during the day. Unless of course they aren't generating much or I'm using a lot.
My leccy is around £25 a month for a large detached home stuffed with gadgets. I've already upgraded everything to low power draw like led and a rated equipment.
Plus TV's do firmware updates in standby, etc. I'd hate to brick a TV by having it on a schedule power down overnight.