Curious why Seiko's spec sheets for their movements

[larryccf]

state such large ranges for time accuracy - like the 6R15, iirc sez "-15/+20" and so many folks report COSC time keeping

my SUMO over 10 days is showing a total of 20 secs fast, which boils down to +2 seconds daily

anyone know

[Lol-x]

My guess is so that people aren't going into Seiko service centres with their warranty card claiming for an adjustment and costing Seiko money for watchmakers performing warranty adjustments.

[pickettt]

Japanese manufacturers prefer to underpromise and overdeliver.

[toxicavenger]

Originally Posted by pickettt

Japanese manufacturers prefer to underpromise and overdeliver.

I wouldn't say that is always the case. Especially with the 6r15 and 8l35.

[pickettt]

Originally Posted by toxicavenger

I wouldn't say that is always the case. Especially with the 6r15 and 8l35.

I don't own either. What's the story on them? I just know I've got sub $300 Seikos that are not more than +/- 6s

[toptier]

Anecdotal: my 4-y/o SARB017 (6R15) runs at an average of 2-3 seconds/day when worn or dial up.
In comparison, my 1-y/o SLA019 (8L35) runs for about 8-9 secs/day.
I'm totally okay with that as a casual office user, but possibly from a professional diver PoV, one would definitely want COSC standards for their diver watch at the very least.
It''s crazy that Seiko regulates only their GS movements..

[Jostack]

If I had to hazard a guess, I would say they know from testing that these movements fall within this spec after their mfg process is complete. They probably have a procedure for setting timing that involve hitting some target metric without having to full-on spend time regulating. Using a method like this may likely allow the vast majority of movements to keep acceptable timing without investing valuable time into regulating a watch.

Thanks my uneducated guess.