If it could be told in 90 minutes, why drag Mildred Pierce out to 6 hours?

Half-way through - three "parts" - of the HBO "Mildred Pierce." Reminds me of: I used to be in a writers' group (PAWs, Providence-area Writers), and once presented a story and some in the group said: It should be a novel, and my thought was, sure, I could spend a few years and build this out as a novel, and when I'm done I'd probably look back and say: I could have told the whole thing as a short story. A work of literature, or film or TV or whatever, should have no unnecessary "parts" (Strunk and White, q.v.). Mildred Pierce was a reasonably good Joan Crawford romantic melodrama about a woman's struggles, triumphs, and defeats, circa 1945 (set in the Depression 1930s) - and it was probably about 90 minutes; if the HBO Todd Haynes mini-series could add to this by expanding the story to six hours, well and good, but it seems in watching it that it could definitely be told in 90 minutes flat: the scenes are extended forever, to no purpose, the same information is conveyed again and again, the sex scenes seem ludicrous, the music is dreadful - the strengths are two: Kate Winslet's acting - she's always a total pro - and the period details, which seem pretty accurate though it doesn't look like Glendale, Cal. Haynes is a very indulgent writer/director and I'm not sure what he's doing with these characters but it certainly seems like they don't belong in the same family: a no-good two-timing dad (who at times is really kind and thoughtful?), a bratty and spoiled teenage daughter (who alternates between mother's best friend and deepest foe), and Mildred herself: sometimes a career woman, sometimes a set-upon wife, sometimes ashamed of having to work, sometimes proud of same, devoted to family but willing to run off at the drop of a proverbial hat with the first handsome guy she meets: inconsistencies and confusion of character may have been tolerable in a shorter movie but in this six-parter with its leaden pace we have all too much time to ponder the incongruities and absurdities.