Arknights PSA: How Best To Spend [Headhunting Data Contract] and [Headhunting Parametric Models]

First off, if you are aiming to spark one of the 300 pull pity Operators, don't forget to finish your pulls! You don't want to end up with 299 and be one short of your operator!

You get one of this currency for each pull on the banner. It can be used to purchase specific operators in the banner series. 300 for a six star or 75 for a five-star. You can spend this currency up to three days after the banner ends, at which point, they get converted to Headhunting Parametric Models.

• If you already have a full potential (pot 6) of the five-star, then it is recommended to use extra currency to buy duplicates of the five star. This is because each duplicate after full potential will earn 8 Yellow certs, and the token can be turned in for another five, for a total of 13. Yellow certs can then be used  to purchase specific 6 star Operators or headhunting permits, which are VERY limited resources. (Do NOT purchase five star duplicates if you are NOT already at full potential, since You will only get eight certs.)

Three days after the banner ends, your [Headhunting Data Contract] get converted to [Headhunting Parametric Models] at a rate of 1:6.  They can be used to purchase development materials.  The efficiency of buying these materials can be seen below. (Source). If you find the images below a bit confusing, a TL;DR would be: in the "sanity/cert (buy)" column, the higher the number the better.

More information on these and other currencies can be found in the guide below: