Speaking of series with a LOT of original music written over the years, Gunsmoke comes to mind...because it was on for TWENTY years (and that's not even counting all of the post-show TV movies, which I think pushed the lifespan of the series to almost FOUR decades!)
So given its longevity, even though I'm pretty sure there were a number of episodes without original score (particularly in the first decade of the show), clearly Gunsmoke would require an INSANELY huge set to be a complete scores release a la Star Trek: The Original Series. Even for the show's biggest die-hard fan who is also obsessed with the music, I can't see more than a dozen people in the world being willing to shell out $600 for a 48 CD set or whatever it would be.
Columbo initially had seven seasons, yes, but season 6 was only three episodes, season 7 was five episodes, season 4 and 5 were only six episodes each...plus that scoring was usually fairly sparse. In contrast, Gunsmoke had 20 seasons but the first six were 38-39 half hour episodes EACH! And even when the show went to hourlong, the next several seasons were still 32-38 episodes each! (And even after the show went to color, it never dipped below 24 episodes a season.)
So I think that a comprehensive release of original music written for Gunsmoke would just be an insane undertaking, with an initial 4 CD set making the most sense, to gauge interest among film music collectors for the show. If that thing sells like gangbusters, maybe a Volume 2 could be possible. Apparently LLL was so impressed by their sales of the 4 CD set for Wild Wild West (another CBS western show, though not as long lived) that they are considering a Volume 2.
As a Goldsmith fan I would still hope that at least 1 CD out of the initial set would be dedicated to all of his music for the series (all six of his original episode scores should fit comfortably on a single disc)... but in case there never was a Volume 2, I would also hope to get the complete scores contributed by the following: Bernard Herrmann (three episode scores according to IMDb), Bruce Broughton (five...and we know Intrada won't forget him!), Franz Waxman (two episodes...though I think maybe it was a single story two-parter?), Herschel Burke Gilbert (two), Leith Stevens (five), and one-offs by the likes of Jerome Moross, Paul Dunlap, Leonard Rosenman, William Lava, Gerald Fried, Ernest Gold, Leigh Harline, and Elmer Bernstein! WOW!
Come to think of it looking at that list of scores I'm dubious whether even all by those bigger name composers could fit on a single 4 CD set...so it might actually be good to commit to two volumes to start with, at least, and if that happens the Goldsmith, Herrmann, and Broughton scores could potentially be split over the two, to ensure that the second volume sells well too.

Plus there are plenty of perhaps slightly lesser known but still talented composers who could then be put into the mix including Jaime Mendoza-Nava (one episode), Allyn Ferguson (one), Nathan Van Cleave (four), Lyn Murray (four), Jerrold Immel (six), Richard Shores (seven), Morton Stevens (TEN! those would definitely have to be split over two sets), and Fred Steiner (a whopping 28 episodes according to IMDb...clearly not all of them could be represented, or at least they'd have to be represented by only one cue each!) And it's possible that some of the many composers who worked on the series but I'm unfamiliar with could also have worthwhile scores to include. See the problem? Still, I hope it doesn't discourage a label from tackling this series considering all of the composing talent involved.
Something like the well-regarded but shorter-lived CBS western Have Gun - Will Travel would be much more straightforward to tackle as a single 4 CD set, I think:
Besides two Goldsmith scores (which will help sell anything!), there’s of course the pilot score by Herrmann (some of his less inspired work though IMO), and at least one score each by Moross, Rosenman, Dunlap, and the less well known but still talented Shores, Marshall, and Jeff Alexander (who I love for Support Your Local Sheriff).
Three scores each by Leith Stevens(!) and William Lava (I’m a fan of his from his work on the Disney Zorro). Four scores each by Lyn Murray and Nathan Van Cleave. Seven by Fred Steiner...
So yeah...this is still all a long-winded way to say, "depends on the series!"
Yavar
EDIT: I just remembered that three Gunsmoke scores have been commercially released (a Herrmann, Moross, and Waxman) by the Film Music Society over a decade and a half ago:
http://www.soundtrackcollector.com/cata ... ieid=69873No idea if they were complete on that disc, or if those scores' presence there means they could be left off a label's new box set for the show...but it's another potential consideration while producing a set!