Whenever I Practice 14.1........
When I practuce 14.1, it's always with me playing the opening safety shot sending 2 object balls to a rail (hopefully not more) and leaving the cue ball as close to the head string (kitchen) left corner rail as possible. I favor using right english on the opening shot on the right corner ball versus playing the opening shot with left english lightly striking the left corner ball, i.e., thus bringing the cue ball as near as possible to the right head string corner rail.
If I don't get an excellent safety leave for my imaginary opponent, I play the opening shot again until I can at least get it down to where my imagnary opponent has at best a very low percentage, difficult cut shot at an object ball 7-8 feet away from the head rail. Once I get the first safety opening right, then I do play it all over again right away to see how close I can duplicate it.
I do the opening until I can get the opening safety shot down at least twice......I mean once could be just dumb luck........for it to count, it has to be repeatable otherwise you really don't know fer sure if you have it down. Then, and only then, I start normal 14.1 play against my imaginary opponent using safety play when I do not have a shot. But rest assured, if there's any combo I see in the rack, I play it first........I mean that's the pure fun of straight pool.......it's like the home run in baseball or a great TD catch.....same thing........breaking up the main cluster is just an exhilarating feeling........Pow....Bam......balls scatter and you look down at a open table of balls awaiting your mapping decision.
I try to select my main break ball and a back-up break shot after pocketing 5-6 object balls into a new rack (9-10 balls left on the table) or at least by after 1/2 of a new rack of balls has been pocketed......you need to allow for a sufficient number of balls left on the table to adequately map your cue ball position play to run out the table. When there's still 11-12 object balls on the table, it's too crowded and there's still too many variables and unintentional bumps of the cue ball that can ruin, or else really complicate, your final cue ball position outcome.
Anyway, I always play the opening shot as seriously as if I was in a match......you never get to practice the opening shot too many times........when you can make a great opening break shot leaving your opponent with no shot whatsoever,......none, zilch, zero,.....not even some wild-eyed, crazy combo attempt........when you can do that at least three (3) times in a row, then you can stop practicing the opening safety shot. Up until then, keep doing it all the time because you really aren't very good at it......and since you don't get to practice this shot when it counts for real, always take advantage of practicing the opening break shot whenever you get the opportunity.