LOL just wait until you have 30+ snakes (it's coming) turning those on and off all day will drive you and the snakes insane, but will work. I use a 24 hour plug in timer (Walmart .... $4) to turn my lights on for 15 hours a day.
Now you have me wondering, if you have a UTH and no thermostat to turn it off automatically, how do you know it's not 100F+ under the substrate or do you have 2 probes? The reason I ask is because the heat from the light will not penetrate thick substrate. It is important to remember you now have 2 heat sources (UTH and light), therefore must ensure neither one gets too hot. You should be measuring the hottest part/s of the viv that the snake can come in contact with, both above and below the bedding in your case.
Personally I have no preference between store bought or home made thermostats, the latter is less expensive, it just doesn't look as "pretty" as a store bought. They both take the same amount of time to adjust to correct temps, so the choice there is purely yours to make.
In a nut shell, you are not F-ing up (made me laugh), with a few minor tweaks your set ups are ideal and safe. (temperature wise)