With 24 minutes per episode you should be able to watch 20 episodes in 8 hours. Assuming regular 40 hour work weeks it should take you slightly over 6 weeks to

With 24 minutes per episode you should be able to watch 20 episodes in 8 hours. Assuming regular 40 hour work weeks it should take you slightly over 6 weeks to watch them all, or slightly over 30 working days. Which you can probably argue still counts as a 'month'. The difficult part is convincing someone to let you watch the Simpsons full time for 6 weeks.