Trigger control is key, but there will be multiple factors at play.
In my experience, take it for what it's worth and that might not be much, ammo selection is the most important factor for precision. One can be well practiced in technique, yet load up a round that the rifle doesn't like and patterns can go from low MOA to high WTF.
There are also physical factors such as barrel resonance and thermodynamics that will play a huge role in consistent shot placement. The barrel heats heats up, but not always evenly. Temperature fluctuation throughout the barrel can change its resonance and produce inconsistencies in shot placement. Learning how your barrel behaves as it heats/cools and adapting a consistent shot cadence will help overcome this issue.
That's all before you get into worrying about your breathing and environmental factors, wind, temp, humidity, etc. Not many of these factors are under our control, so learning to work with the varables and adapt can lead to some really tiny groups on paper. Once you get all this figured out and documented in a shot log, something changes and you get to figure it out all over again. My rifles and mother nature have a way of reminding me that I don't know $#!+. Shooting for precision is both one of the most rewarding and most frustrating endeavors I've undertaken...
