Here you will always be able to see progress on the upcoming four chapters of the current volume - if there's less than four planned chapters left in a volume, then the progress bars will only run until the final chapter of the volume. The reason it's not all chapters of the current volume all the time is because my chapter plans don't always go to... well, plan. It's happened on several occasions that I've had to slot in an additional chapter because I couldn't fit all that I wanted in one (since I'm trying to keep chapters within the same length span of 2000-4000 words). This, plus me having an entire folder of drafts of scenes for future chapters, is why the progress bars can get weird sometimes and there's a nonzero chance that there'll be times when later chapters have more progress than earlier ones.
For the first four fruits, each fruit represents a 1000-word threshold. All gray fruits means I've written absolutely not a single word of the chapter. One half coloured means I've started writing it, even if it's just the opening sentence, but is less than 500 words. One coloured means I've written between 500 and 1000 words, and so on. Until the fifth fruit - four and a half fruits means the writing's all finished and it's in proofreading/editing, while a full five means it's all done and ready to publish! This means that four full fruits indicates over 3500 words written, which is a length not all chapters actually reach, so it's not unlikely that a chapter will jump from 3.5 to 4.5 fruits. Sometimes larger jumps can happen, some chapters don't even reach the 3k mark. A chapter will at least never go over 4000 words - if I hit that, then that chapter needs to be split.
If a chapter gets ready to publish, and the following chapter has at least reached the proofreading stage, then that chapter will be published the following weekend. The progress bars themselves will be updated at the very least once a week, at some point during the weekend, and can update more frequently if I feel it's called for. They will naturally also always be updated when a new chapter gets published.