LUD changes
In this particular case after I submitted my RFE, it changed first on August 13th, the day they received my response and again on August 17th or 18th. After that it never changed until I got the approval.
However, for a long time my status had never changed. It was only after I submitted a change of address in January this year, my first FP results were updated after more than year. After that any time there was any activity it was immediately reflected on the USCIS website - second FP notification, second FP results, RFE notifications, etc