The Etiquette or Rule about Practice before a Match

These past few weeks I have played in several tournaments where there were plenty of novice bowlers. At each event some of these new bowlers, as soon as they knew which rink they were scheduled to play on, began throwing practice bowls on that rink. This is bad form. It can be embarrassing as well because, as happened on one of these occasions, the tournament committee came on the loud speaker and ordered the offenders to stop bowling where they were practicing. I do not know whether it is an actual rule or just proper bowling etiquette but practice on the day of a tournament is acceptable only if it is done at right angles to that day’s competition direction. All I can find in the Laws of the Sport of Bowls Crystal Mark 2^nd Edition is:

12.3   If, before play starts, a player in a competition or game plays on the same rink on the day of the competition or game that player will be disqualified. This does not apply to open tournaments.

From this it is not clear when such action is actually unlawful rather than just gauche.

The reason for the admonition is fairly obvious. Part of the skill in lawn bowls is the ability to quickly learn what is the proper grass, what is the narrow side and what weight to play on the assigned rink under the given weather conditions, and no player on any team should begin a match with special knowledge just gathered before play starts using unofficial practice bowling.

In Ontario Canada where I compete, there are no trial ends allowed in tournaments so I can understand the extra nervousness this creates for novice bowlers; but, good form is important and we should not violate it.