Actually it’s a mix of both. I initially had the predecessor smart-plug (HS105) and used those primarily to control lights on/off. Then I did two things: for lights that are not hard-wired to the house I purchased some smart bulbs (Wyze/Feit) and for those that are hard-wired I installed smart WIFI dimmers (Feit). So now, all my lights are smart except few (bathroom/garage/attic…) as there is no need there.
Then, fast forward few months, I acquired the Sense, and learned a bit more about DCM and smart-plugs with energy monitoring, and how expensive the TP-Link HS-110 are ($100 on amazon). The KP115 were not available then. Once they were, I got few to help Sense but also control some of my devices. Granted, 7 is a bit of an overkill, but I convinced myself they’ll pay for themselves in a while.
So, the only one (KP115) I turn on/off is the one running the grow lights (600 W). The others, (computers, fridge, aquarium, …) is just to have an idea of the consumption.
You need not get only the KP115. The HS105 are cheaper ($20 for 2×) and are suitable for basic on/off and other home automation e.g. control lights when away from home.
One word of caution though. This Home Automation hobby is a bit addictive and the last thing you want is buy the most expensive/promising hardware out there. Some people sell smart switches for $50 a piece and granted, those look slick, but if you have 30-40 switches in your home, that’s quite an investment. Go slowly, learn along the way, and only invest in what you need today. Tomorrow, no one knows for sure if this technology will be relevant, especially that many devices use the 2.4 GHz WIFI network, and that’s getting slowly cluttered.