In my airline, the ISA dev on the OFP for TOC is entered in the perf init page whereas we calculate the ISA dev for destination airport based on what the ATIS says and use that in the descent forecast page together with QNH.
Refreshing the next waypoint on the legs page during descent recalculates ur descent path based on winds experienced at that moment so the trick I use
in order not to be high is to refresh when there's a TWC.