Years back I made lagers that fermented for 2 weeks. Now a 1.050 Pils will be done in about 5-6 days, higher gravity a few days longer. Use mrmalty.com to get the right yeast volume to pitch, lots of O2 before you pitch, and some yeast nutrients in the boil. I did not used to do all of that, but it is needed to make better lagers.