This reminded me something similar I do:

In my bedroom I have a clock from Ikea which I think I've never changed batteries (or only once?). ~Ever since I got it, it goes around 5minutes ahead of local time every 6 months. I noticed this soon enough, but I liked the idea, so I deliberately set it to be 5minutes ahead of local time (this means after 6months it's ~10minutes ahead).

After some years, I got another clock from ikea. I now have two clocks. One clock which supposedly says the real local time and another one (the older one with the bigger display) that shows the local time 5minutes in the future.

Though both drift a few minutes ahead as time passes and on top of that I tend to be too lazy to fix the ±1hour of the daylight saving time on the old clock, so it's a mess and many times I end up doing calculations when I wake up to figure out the time, lol (Like, the big clock says it's 08:00, but I have to add 1hour because I didnt add the daylight saving time and I have to subtract 10minutes, because 7months have passed since I last set the time right, thus the actual time is 08:00 + 50minutes = 08:50)