Fermentation can't be monitored with the airlock or a watch. Your hydrometer is you answer, when the gravity is the same for 3 days in a row your done. But just knowing that your Gravity was 1.072 8 days is most likely not enough time and in fact after the "primary" fermentation is done you should let it sit longer to do a "secondary" cleanup after itself.
This is the most common topic in the beginners forum and simple search will find that a lot of people just wait 3-4 weeks for things to finish up and then rack and either bottle or keg the beer from there.
On tap: #79 Berliner Weisse 1.030 9/20/12, Flanders, Barleywine, Wild Blonde (1.045 blonde hopped up and fermented with WLP644), #80B rett Saison
Fermenting: #82 Galaxy IPA, #83 Black IPA
Aging: #67 Bareleywine 1.116 11/07/2012, Flanders 2 batches 1.056 and 1.060 12/12/11 and 3/26/12, Kriek, 1.052 12/11,