Personally, IMHO, USBC had a good thing when they announced the Red, White and Blue Patterns, designing certain patterns for all alleys to try and see which will work best. USBC decided for some reason to make the house shot the Red pattern, and that took out the Blue and White out of play.
Because of this, league bowling has become a joke and only the employees (mainly mechanic and manager) have the edge over all bowlers (assuming there are no pro bowlers in your league). If USBC would come up a pattern for the Red, and told all alleys they must use one of the three in order to comply with USBC, bowling leagues in my mind would be fair again.
The sport has gotten so technical, I firmly believe the bowler has the right to know what pattern is out there so they can decided what their next purchase of equipment is.
So to answer the question, the league shot should NOT be a secret.