Re: Best Season-long Story arc
Not really. The Entropy arc consists of only the 18th season. The entropy caused by the Logopolitans' inability to contain the destruction of the universe created the E-Space entry for the Doctor and Romana to get in. And thats all after the Doctor started using the Randomizer again. The story concludes in Logopolis.
Its a subtle arc, I admit, but the intent is there.
The Master's Return arc is only three stories long, and consists of the last two stories of the 18th season, with a forced tag-along of Castrovalva in the next season - Bidmead didn't think the story would be followed-up upon so directly before they called him to write the Fifth Doctor's opening story.
Finally, I made the thread about the season-long arcs, ones that run more than a couple of stories in a given season. Thus why I also ignored other arcs, like the Black Guardian trilogy in series 20 of OldWho.
Entropy was only a factor in Logopolis not some season long story arc, season eight isn't a story arc either other than the MAster there's nothign tying the stories together. And really David Tennant's final stories aren't even part of a season just a series of specials. The Key To Time was the series first ever season long story arc and The Trial Of A Time Lord was the next, but they were new concepts even back in those days.
The greatest science fiction series of all time is
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or all in a bunch to back it up!"
--- Harlan Ellison, from his introduction
to the PINNACLE series of Doctor Who books