A/THR is optimized to work with AP ON.
When you manually follow FDs on final and decided to keep the A/THR ON, you do not need to do anything if your IAS is between Vls and Vapp+10 (I assume you're on the ILS...).
This situation is usually transient and that's why we add +5kts when A/THR is ON for APP.
On the A330, it's really not unusual to fly the entire APP with Vapp-X when A/THR is ON.
Personally, I don't like it, so A/THR is OFF most of the time.
So to answer your question, I'd say it depends on your energy state: flight path deviation/ROD/current wind/expected wind/thrust demand ordered by A/THR/height...