I would view 10 reqs as a relatively low quantity. A more appropriate quantity to aim for is probably 100 but you start to sell when you reach 200.Well it depends on your Spartan Rank. I’m SR17 I think and so I sell when I have more then either 10 or 15 depending on rank. I don’t sell ultra rare or legendary ranked REQ’S tho
At the current state, I sell a significant portion of all reqs with few exceptions that are given below.
There are few notable exceptions to this rule like that I do usually sell some of the listed Power Weapons or Vehicles when I get too many of a given type (above 200).