Depends on your story. For a competition entry Tapas requires a minimum of 1500 words per chapter, and 30 chapters, so you COULD use that as a guideline, but my suggestion is to just go with your gut and make your stories as long as you feel tells the story best. Or, write what you want to read.
My novel ended up being a lot longer than planned because I knew there was more I wanted to add to the story. I think you should judge the idea as worth adding or the chapter length, worthwhile, if in the end it's something you'd WANT to read, and especially if it's not something you'd skim over to get to the next 'good part.'