We all hate duffing shots. The only way to reduce or stop doing this is by practicing.
Rule 7 is very clear about what can and cannot be done during a stipulated round
7-1. Before or Between Rounds
a. Match Play
On any day of a match play competition, a player may practise on the competition course before a round.
b. Stroke Play
Before a round or play-off on any day of a stroke play competition, a competitor must not practise on the competition course or test the surface of any putting green on the course by rolling a ball or roughening or scraping the surface.
When two or more rounds of a stroke play competition are to be played over consecutive days, a competitor must not practise between those rounds on any competition course remaining to be played, or test the surface of any putting green on such course by rolling a ball or roughening or scraping the surface.
Exception: Practice putting or chipping on or near the first teeing ground or any practice area before starting a round or play-off is permitted.
Note: The Committee may, in the conditions of a competition (Rule 33-1), prohibit practice on the competition course on any day of a match play competition or permit practice on the competition course or part of the course (Rule 33-2c) on any day of or between rounds of a stroke play
7-2. During Round
A player must not make a practice stroke during play of a hole.
Between the play of two holes a player must not make a practice stroke, except that he may practice putting or chipping on or near:
a. the putting green of the hole last played,
b. any practice putting green, or
c. the teeing ground of the next hole to be played in the round, provided a practice stroke is not made from a hazard and does not unduly delay play (Rule 6-7).
Strokes made in continuing the play of a hole, the result of which has been decided, are not practice strokes.
Exception: When play has been suspended by the Committee, a player may, prior to resumption of play, practise (a) as provided in this Rule,