Depends on your use-cases. If you try to update one specific element in there it might be easier to override the whole document than to try and write code that maps over that document to find the specific element and updates the attribute :).
The same reasons that working with an inline array can be harder than working with relations.
E.g. for an inline array you would have to cut the array in two, update the element you need to update and glue it together or map over the whole array and do an if test to check which object that needs to be updated (very inefficient). While with relations everything receives its own object and you just grab the reference and update that specific small object.
Both are useful in certain usecases, it’s a careful consideration . I would say, try out what works for you.
Is this always new data? Since if this data is often the same that you are going to override then it’s also a bit of a brute-force approach right? I would strongly recommend calculating a diff if those are the same elements and you want to push down the costs. Also, because FaunaDB will store versions for each of those (even if you set versioning very low, it will -at this point- always store a few versions, so I don’t think it’s a good idea that you overwrite these docs each minute. Fyi, we are working on a feature to respect that versioning setting exactly).
If each minute 75 new elements arrive than 108k write ops is just the nature of your application and given that you get 100k ops for free, its actually still ridiculously cheap no?