Twisted Tales has been pretty stable at about 10:1 views to subs. Right now I've got 1,762 views, and 151 subs (I've been stuck at 151 subs for weeks--I keep losing a subscriber, then gaining a new one. Lose another, gain two. Lose two, gain one. Ugh.). I've got twenty six chapters in this story, and I'm pretty pleased with my ratio of how many viewers end up subscribing.
Breaking Magic isn't doing quite so well with a ratio of 16:1, with 320 views to 20 subscribers. More telling, I think, is that it is 20 chapters long, nearly as long as TT. TT is clearly an outlier since it ended up on staff picks and got a boost in views from that, but I'm genuinely surprised that TT had a better retention rate than BM. TT is very much a "for fun" novel, sort of silly and impulsive.
Though, I'm pretty sure I know what the problem is in BM: a less-than-stellar first chapter, and a sloooow burn on the romance.
I'm pleased with my situation on both overall, though. Especially TT. I'm never going to hit the big numbers like some of you have (5k subs just blows my mind!), but 151 is waaaaay more than I was ever expecting to achieve! All your beautiful art makes me wish I could draw better, though -_- So many gorgeous comics. I subscribe to some just to stare wistfully at the art!
Also, I totally agree that number of episodes matters. I just subscribed to Flower Eater, which reached 1k subs after SIX (6!!) episodes. It's plain to see why, the art is absolutely enchanting, and the concept is so unique. So yeah, sub ratio to chapter ratio is important to understanding relative success too.