This is probably a really stupid question but I tend to severely overthink things like this. I usually ferment most of my beers in primary for 4 weeks. Unless I’m truly aging, I don’t worry about secondary.
I have a beer that has been in primary for 5 weeks. Do I have any off flavors to worry about?
If not, how long can you keep a beer in primary before you need to worry?
5 weeks is not an issue. As far as how long I would think 8 weeks or more depending on OG/ABV
You’re safe until at least 8 weeks, maybe 10. How do I know this? I am a VERY VERY VERY VERY LAZY brewer.
I’d say even longer assuming yeast health is good overall.
My question would be, why leave things in the fermenter that long as a matter of course?
My question would be, why not?
In general, I feel, the more patient we are, and the less messing around, the better the beer will turn out.
Not a matter of course. Just brewed and then got really busy for awhile. Usually, I bottle/keg right at 4 weeks.
Just as an open question, ? What is High OG or ABV to worry about your beer needing a secondary fermentation vessel or to be in the primary less than 8 weeks? Also I assume you mean high OG and ABV I hope I am right on that one two
Sorry, I meant four weeks as a matter of course. Nothing wrong with it, of course, it just seems unnecessary.
Fair enough. I guess it’s at least partly a mindset I picked up from commercial brewing. When the beer is finished, drink it. Rinse and repeat. 
Guess it’s just what I’ve always done 4 weeks…Give it time to ferment out. Suppose I could shorten it up.
I’ve left clean beer in primary (intentionally) for over a year and brett beers for 2.5 years. No off flavors from extended contact time. I would not be worried about the difference between four weeks and five weeks. I would be more concerned about leaving beer best consumed fresh hanging around for a month before packaging.
I have done 6 weeks with no issues on some Saison’s.