I second that. It can even be helpful if you want to get your bearings on what material you already know and where the new stuff comes in. It's good to see some familiar sections and then see them expanded.
What I don't like is reading and then realizing that it is in fact the same material just paraphrased with different words.
Concerning Jaiman and flow storms. One map I really appreciate is the map of essence flows in the Jaiman source book. I have used it repeatedly in order to check if the party was indeed located within one of those flows. If they were, I rolled a percentage chance whenever one of them cast a spell. On a success, the spell went through as planned. On a failure, they did not cast the spell they wanted to. I had them roll 1D100 to see where they actually landed. A beautifully chaotic turn of events that could be. Yes indeed 
Hah, I try not to ramble and repeat myself, but I also hate to mention something and then send the reader to some other location in the book for a more complete description when I can summarize something there. For instance, now I am working on the Wuliris GM map, with dozens of keyed Items. In the key, I am including a descriptive line for a place, and for the more interesting places, I do make a reference to later in the book where it is fleshed out, but I also give a very brief description here.
As for the Flows map, well I can certainly do more. I am curious how much other GMs use the Flows, Flow Barriers and Flow Storms as a regular part of their games???
