So, I have be logging the variance in time for the past 20 + days, and it seems that my watch (Omega Seamaster Aqua Terra; Co-Axial) is consistently -4 seconds. When I first got the watch, is seems that it was only losing 2 seconds consistently for the first week. The question posed is should I send it in to have it regulated. I would hate to open up the watch, and have it be gone for a period of time. Is -4 seconds an issue?
Did you try leaving the watch in different positions when you're not wearing it? Dial up, dial down, crown up, crown down, crown left, crown right... Making sure the watch is fully wound of course. I believe the spec for your watch is -1/+6 sec per day. If it's still slow you may want to have Omega adjust it for you.
Regulate it, it's cheap so no reason not to and -4 is outside Omega specs. Positive is always better to have.
Consistency in rate on the wrist is a good thing to have, and having it "adjusted for wear" is something that watchmakers would do for free after a service. I see no reason not to. But you do want to try a gainer position overnight if you could. Your watchmaker should be able to tell you what the rate is, you'll want the watch in whatever state it usually is at bedtime. Tom