This is not quite a 100% answer to your question, but based on experience, I believe that you will find it useful.
I made a somewhat similar application, when I had to update (redownload) a very large number of XML files (up to several thousand).
The one-by-one method was pretty slow, but with good NSOperation and NSQueue it worked fine, without the UI freezing or crashing on the first iPad. I believe that for the maximum number of files it took no more than 15-20 minutes (somewhere more than 5000 operations with 5 simultaneous downloads), on a Wi-Fi connection.
When I tried the zip method to find out if it would be faster / better, this caused iPad 1 to crash due to high memory usage. And the zip size was about 100 mega if I remember correctly
I suggest you go to the first option. 1000 requests per day are not such a large number, and therefore the user does not need to wait until the entire archive is downloaded, but he can read the read pages without any problems.
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