I didn't see a post about this so I thought I'd make one. You can now read collections/series in a similar fashion to books! I don't think this feature was added until recently or I'm blind.
Find a manga that belongs to a collection and scroll down to the chapter list, like this. Then click the title of the collection.
You should see a new big green button for reading a full collection, just like a book.
Thanks for implementing this feature!