Lesson Before a Tournament
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IMO it depends on whether the adjustments are a small tweak that corrects a swing flaw or more of an overhaul that requires a lot of reps and some painting by the numbers until it becomes natural.
In general it's best for me to go by an old saying in baseball. "Practice your swing off the field. Trust your swing on the field."
One or maybe two little keys like maybe dropping into the slot, not swaying off of the ball, leading with the butt end of the club, posture at set up, or keeping my head still are about all I can handle while playing. When I'm playing my best all I'm thinking about is where I want the ball to go and what shape and trajectory it needs to get there.
Tell the golf instructor that you have the match, and even if you're given a long-term practice plan (i.e. something to keep working on, but which may cause a slight disruption to your typical shot pattern), you still need a little feel or swing thought for your tournament.
For example, let's imagine someone is hitting low pull cuts, and we shift their path to be more to the right but they don't quite manage to control the face very well - so they hit a lot of pushes that don't draw back to the target (or maybe they fade a tiny bit - but that'd be rare). We'd tell that person to simply play the push shot, and their feel would be whatever it was that clicked for them to shift the path more out. They could line up left and simply play the push all day, then continue to work after the tournament on getting it to draw back.