Ummm - thanks. I know how to measure the gravity. I just don't like to geek out over brewing too much, open the fermenter too often or worry over my beer too much. I've read plenty that says you can get a good feel for eyeballing when active fermentation is done and that works ok for me. I stopped measuring the obvious after my second brew. I know for other people it is all about the measurements and the notebooks - but, you see that kind of behavior with all hobbyists. If I was brewmaster for Heineken I would be an anal freak measuring everything and coming out with millions of identical bottles of beer. But, I'm cooking up some beer for me and my friends and it is pretty hard to make it worse than what is on the shelf at the store. So, yeah, I know what gas is coming out of the lock and that it isn't a super accurate measure of the gravity or the alcohol content, But, it seems a good rough guide for when active fermentation has slowed.
Are you saying that it is at all likely that a lock bubbling every 7 seconds is done with primary? That doesn't seem likely. Do you really think I should open it every day and measure its gravity when it doesn't seem close to done? I've never seen that advice before.
Like the doctor says - common things occur commonly. Have you actually seen this before - active fermentation complete and a seven second interval on the bubble?