Still Fermenting after 8 days??

I was just wondering what people have experienced with yeast and fermenting times.  I normally have been using dry yeast so far and find that the yeast usually is settled and completed fermenting after about 5 or 6 days.  This last batch I was able to get some live yeast from my local brewery and after 8 days its still active and busy.  I did make a rather strong beer this time (target of about 8.9% ABV) so I am sure there is plenty of work for the yeast to do - but just wondering what other people's experience has been regarding how long they have had yeast remain active in the fermenter.  Any input as to the differences between dry and liquid yeast as it relates to their active time in fermenting would be appreciated...

Many many variables- temperature, SG, yeast strain, etc. Keep an eye on  Airlock activity and use gravity readings to verify. If it's not at final gravity and activity has stopped, you ran out of yeast/oxygen. These brews need aeration before adding  a strong starter. If so, you may need to repitch with a yeast that is known to finish high gravity types of brews.  I don't return the reading sample to the fermentor,  just drink it.
I have a cold fermenting lager at 50 f still going after 24 days-it's at  1.020.and it started at  SG- 1.050.  Needs to get to 1.010.  The cold slows down things but makes for smooth clean tasting beer. It's also carbonated like crazy without trying, and bubbles can give false high readings.  So De- fizz and check SG with hydrometer. Also, I have had carbonation keep the airlock going when the brew inside has reached terminal gravity. It looks active but it's just carbonation bubbling off. That's why the gravity reading is used to verify. I'm thinking your high gravity brew is going to take longer in every phase like mine do. Don't be impatient just let it take its own time and be happy. Relax and have a homebrew, if you dont have one have a craft brew. CHEERS

Just a follow up on this post.  After about two weeks in the fermenter it appears I have hit my final gravity and am now dry hopping.  As to some of the questions posted - My temperature in the fermenter is between 65-67 degrees, my starting gravity was 1.082 and I believe the yeast strain was WLP 001 although I am not 100% sure of that.  Just as additional information after 8 days my gravity reading was 1.030 so I was a little concerned.  But it appears that it just needed more time.  It now appears to be pretty much done and gravity reading this morning was 1.012.   

The yeast doesn't follow your schedule. You follow its schedule.