I generally don't start unfinished serialized stories unless they come with a lot of recomendations and the author seems to have a track record of (1) finishing what they start or (2) posting updates regularly for a long while (or (3) the author asks me to beta-read or edit as they go along). When I do, I'll tend to read a month or more's worth at a time, bookmark the latest chapter (with a date in the bookmark), and come back to it a while later. There are a handful of webcomics and webserials I read every time they update, but the majority I read only once every few weeks or months.