If you are a UConn graduate student planning to take the prelims, here are my experiences with the ones I took.
Measure Theory: It took me 1.5 months of intense preparation. Even though I had previously seen it in two graduate courses + an undergraduate course, it did require significant prep. time as I worked on a lot of practice problems.
To keep a track of my learnings, I noted down major theorems and intuitions, and problem-solving strategies. These are things that are implicit in a textbook and mentioned by the occasional lecturer, so to make them explicit really helped me understand the nature of objects considered in measure theory.
Here are some rough notes, and solutions to some past prelim problems.
Topology: Some notes. Again, while they are not complete, I hope they serve as a helpful guide in what they do contain (ideas/proof strategies in connectedness, computing fundamental groups with more rigor, and some stuff on universal properties of product, quotient topologies, etc.)
Complex Analysis: Here are my notes. These are much more complete (and exclude only stuff about integration w/ residues), and are a summary version of Dr. Chousionis' excellent notes on the subject.
This prelim is very interesting to study for due to the fact that holomorphic functions have such interesting properties that, a priori, one cannot really conceive of, and, a posteriori, seem hard to justify (but sometimes do offer some intuition).