I have two short stories out as individual ebooks on Amazon and Barnes and Noble. Since they are unrelated (one is supernatural and the other is romance drama) and about 10,000 words each (somewhere around 30 pages for Kindle), I chose to split them up. I think your marketing strategy will play a big role in how you want to package things, though.
I suggest that if you have a series of related works with a large number of stand-alone stories, you should split them up into volumes (1-3 stories per volume, depending on length). The first volume can serve as an introduction to the series that you can then use for the 5-day free promotion through KDP Select, or even better, as a permanently free book through the price match method that some people do through Smashwords. This will hopefully get you ranked on Amazon. Put links or references to your other stories inside so that it's easy for people who like the free volume to find the others in the series that are sold at a regular price.
The reason that I say to split them up is because the free promotion with KDP Select makes your work Amazon (Kindle) exclusive for 3 months and limits your distribution channels (i.e., no websites, blogs, or other retail outlets [B&N, Kobo, etc]). If things catch on, I imagine you wouldn't want all of your stories to be contractually limited, given that you have such a high volume of work. Plus, depending on the subject matter, variations in titles (playing into tags and keyword searches) and cover art might make one volume more popular than another, while still allowing for a sales runoff since they are connected as a series.
Short stories are great because you can release them as singles, mini-volumes, or even large collected editions. I say play around with different packages and prices to see what readers respond to and what works best for you. Since it's free to publish on Amazon, there's no harm in experimentation, as I have found out from personal experience. Best of luck to you.