There are horror stories all over the internet about more or less expensive watches with Seagull movements that run fast/slow by minutes per day or don't run at all or only for a few days.
Well, here's a different version of that story:
My G.Gerlach diver has the Seagull ST 25 (picture G.Gerlach)
This is a 39 Jewel automatic with 40 - 45 hours power reserve (not tested by me) and a 21600 beat rate.
Straight out of the box it ran 15 - 20 seconds fast per day. I wasn't very impressed with that, but not overly concerned either. I have worn the watch on and off for four months now and it seems to be "bedding in" as far as accuracy is concerned with continously improving values.
As it has a hacking feature, keeping track of the timing is very easily done.
I'm wearing it continously now since Thursday evening and since then (it's now Sunday afternoon) it has gained the grand total of three seconds (in comparison with time.is)
During checks inbetween, it has varied from 0 to +5 and currently stands at +3
Now if that isn't good ...then I don't know.
As I understand it from their mile long thread on WUS, G.Gerlach buy grade 1 movements directly from the Seagull factory (none of the dreaded subcontractor rubbish) and also whip it over a timegrapher during assembly ...but still ...not everything from China is necessarily rubbish.
My only criticism of the movement would be that the rotor is rather noisy, you can clearly hear it even over the (normal) "chatter" of a steel bracelet when shaking your wrist.