Do you wait for the Final Gravity to reach its mark before you move beer out of primary, or is there a MAX number of days you will let the beer sit on the yeast?
Yes, you want it to be at it’s FG before moving it and at the same gravity reading for 3 consecutive days. # of days is not accurate. Most don’t secondary their beer anymore. What style of beer is it?
I have done Porters IPA Stout Kolsch etc Do you worries about off flavors in te primary to long?
I normally won’t leave the beer on the yeast for more than 3 - 4 weeks. Depending on how you brew it may be hard to know what your final gravity should be. Extract (unless you have brewed with that specific kind before) can have all different levels of fermentability. As a general rule of thumb, if you have maintained good consistant temps where you want them and your gravity hasn’t changed in 3+ days, it’s good to move.
Really?! I wonder how true that is, or if it is just your perception as a non-secondary-aire… :
Experience. YMMV… :
I always secondary. never heard of leaving it on primary 3 - 4 weeks?
I’ve never had to leave them in primary longer than 3 weeks, but have gone away and forgotten about beers before. 
Anyway, 3 - 4 weeks won’t hurt beer.
I guess my 7 - 10 day max is way off the mark then
Naw, “secondary vs. no secondary” is one of those timeless wars similar to “batch vs. fly” or “stainless vs. aluminum” and such. Your best bet is to try both and see which works best for you.
I always secondary, unless its a wheat. I’ve tried both ways, and its much cleaner if I secondary. Each batch varies, but on average it 7-10 days in primary, and 3 weeks in secondary before bottling or kegging. I’ve been told you dont need to secondary if you keg, and just to accept a cloudy first pint or two, but I’d rather have clear beer from the first draw. Each to there own though…
It’s really flexible per everyone’s preferences and method- I’ve done it all which-aways. ROT is once the gravity is stable and close to where you expect then think of bottling safely or kegging. Some stuff takes longer.
+1
Target your gravity and act from there. Some beers will fully attenuate in a few days while others in a few weeks. When the gravity reaches your target only then move it out. For most beers I will go from the primary into the keg which is the secondary.