Opened a support case for this and the behaviour is by design
"Statistics values are saved in 2 places, one in index_stat and one in document. When you make a click-through value in index_stat is automatically updated via document. And then the hits return in the right order."
Found an interesting issue regarding EPi Find statistics, was hoping someone could shed some light on.
When performing a search the result a user selects is tracked. On searches, autoboost is used to promote the most clicked pages up in the results, this is all working as expected.
Problem I am seeing is that if the "EPiServer Find Content Indexing Job" is run, the hit count/autoboost no longer has any effect on the results, even more interesting is that if a previously popular result is clicked just once then full hit count/autoboost comes back into play on future searches.
I am aware that the index job isn't recommended to be run often etc but am still curious about the problem it is causing.
Using Find 13.0.4