Long comics: 2-5 episodes
Short comics: 5-15 episodes
Long episode novels: 3-8 episodes
Short episode novels: 3-8 episodes
For comics, I know it can take a while to get started, so I do try to give some wiggle room.
For novels, I’ll typically make a quick judgement call. If the writing style is entirely different from the blurb, that’s quite off-putting to me.
If the blurb interests me (comic or novel), I’ll most likely read a good bit. It has to be a pretty extreme level of terrible writing or plot for me to drop it, honestly.