DESPITE “THE SOPRANOS’ ” irritating 21-month layoff between seasons, an unscientific survey suggests fans of HBO’s mob drama couldn’t be champing more eagerly at the bit for its March 12 return, as if waiting for ketchup to pour onto a thick, juicy burger. (Click here to read the review.)Drawing too many comparisons to this mold-breaking series — not just content-wise, but in its elevation of cable ratings to heights not seen before or since — is potentially unwise. It’s intriguing, however, to contemplate what “The Sopranos’” widely spaced appearances might say about the shifting rules of scheduling hit programs, and whether dutifully trotting series out at preordained intervals — a strategy tethered to TV’s past — is necessarily its future. Television, after all, was once just a grueling marathon to syndication, churning out 22 episodes a year until achieving that magic 100 number, at which point the producer’s vacation home in Aspen or Maui was virtually assured. Today, by contrast, gratification needn’t be so deferred. DVD sales and downloads provide the means to cash in days and months, rather than years, after the initial broadcast, begging the question of whether some series — ABC’s “Lost,” for instance — might be well served by tinkering with play patterns, counting on an avid fan base to show up whenever and wherever new episodes become available. Granted, deviating from convention — especially with something that’s working — requires considerable guts. For all the talk about original summer programming, it finally took Fox to disrupt the traditional September-through-May TV season, established because big auto makers launched new cars in the fall and kids returned to school. (Actually, the “season” originally ended in mid-April, before it expanded to encompass the May rating sweeps.) These days, there are really three seasons: The one commencing around Labor Day; the other that begins in January, when “American Idol” returns; and the cable-dominated summer. Thanks to “Idol,” Fox rules that second leg, augmented by the successful gambit of playing “24″ in “non-stop” fashion — minus the annoying two- and three-week rerun gaps that plague other primetime serials. Similarly, Fox boldly introduced the escape serial “Prison Break” in August, then locked the show away for four months, awaiting its March 20 return. As with “Sopranos” (albeit with less pent-up ardor), my guess is the audience that watched the November cliffhanger will be back in force. Of course, truly fulfilling this forward-thinking philosophy also means toying with allowing limited-series concepts to run their course and expire with dignity, then moving on to something new. In other words, no “Prison Break: The New Escape,” with some cousin tossed on death row, or “Sleeper Cell: The Next Cell.” So how would “Lost” addicts feel about an extended vacation? More than likely they’d be fine with that — especially if the tradeoff meant receiving a big, continuous burst of episodes before Walt goes through puberty, instead of teasing out 24 episodes over 36 weeks. As for whether their passion might fade, the movie business has demonstrated this much: People pine for the stuff they really like, and no one seems to mind a three-year lapse between “Star Wars,” “Spider-Man” or “X-Men” sequels. If anything, the breather just makes opening-weekend audiences hungrier. Television is a different model, but the anticipation engendered by “The Sopranos” certainly couldn’t hurt a broadcast business that, enslaved by its sales department, for the most part still adheres to a calendar laid out in the 1950s. In a sense, all this boils down to the showbiz adage that counsels “always leave ‘em wanting more.” And if the emperor underscored his stupidity by telling Mozart in “Amadeus” that his music contained “too many notes,” it really is possible that today’s TV maestros might be delivering too many episodes, dished out over too little time. ‘Domino’ Theory: For those who have concluded that basic cable has officially run out of things to televise, here’s additional proof: ESPN’s Spanish-language network, ESPN Deportes, announced that beginning March 21 it will bring dominoes to the screen with its telecast of the 2005 World Domino Tournament, stating, “Our goal is to make dominoes the next mainstream sport on television.” If that telecast does well, “The World Strip Backgammon Championships” and “Full-Contact Tiddlywinks” can’t be far behind.