My newish (I bought 2nd hand, but had only been worn a handful of times) 2021 Seiko Turtle (4r36) is now starting to show some good timekeeping. I bought a timegrapher a while back and have run some experiments regulating with it.
My watch now runs about 10 seconds fast per day if I give it a really thorough hand wind. It does that for a couple of days. Then runs about 10 seconds slow for a day or so, then runs about 10 seconds fast again.
However, after all that, if I don't wind it at all and just wear it 24/7, it settles down and it is absolutely spot on. It's been spot on every time I've checked it (about 20 times, randomly) over the last week or so.
I've regulated the watch 5 or 6 times. Each time I've got it closer and closer. Sometimes running a bit faster, sometimes a bit slower. Was running about 20 seconds slow per day out of the box, so not bad. The beat error was about 2.5 and I got that down to around 0.3 to begin with. I will admit, it's not a process for the faint of heart and I'm glad these movements are not expensive to replace
But the money I spent on the timegrapher was almost exactly the saving I made on RRP
And lume during the day