This course is really all or nothing. You can go weeks at a time without thinking about it but when Prof Fish assigns a problem set, expect to give it your full attention for days on end. The problem sets, which are assigned more or less every other week, can take upwards of 8 hours (Prof Fish even warns you of their length by advising that you start as early as possible). Overall, though, the course material isn’t that tricky once you understand the basics. After a certain point, his lectures seem to cover the same information merely presented in different ways.