The length of the strict scholastic fugue is about 100 measures. It has all the elements that the fugue is suppose to have (subject, answer, countersubject, exposition, episodes, counterexposition, subject entries in related keys, dominant pedal point, one or more strettos, and tonic pedal point).
Of course, it didn't take it very long for this professor to compose a fugue - it was already created in his mind. All he had to do was to follow his mind and write it down. After writing these fugues for more than 10 years, he achieved a real mastery at this.
Just imagine - one fugue every day before breakfast for such a long time!
Some might say - it was easy for him - he was a pro. Yes, except it's not true - every morning he still had to beat his Resistance. But he was strict with himself. He had discipline. He didn't say, "well, I'll first become a pro and then I'll have the discipline." It doesn't work this way. It works the other way around.
In fact, the only thing that differentiates a pro from an amateur is the discipline. Not money, fame, influence, or education. Just strict old school discipline at whatever it is you want to excel.
And the most inspiring thing of all is this: all it takes is to choose to have a discipline (not more resources, more money, or more time). This choice is available to everyone who cares to dream. (HT to John).