The classic way to divide a stream of consciousness into chapters is to highlight a complete thought. It doesn't matter how many words it takes. In a single piece of writing, it can be anything for each chapter. Chapters that are too large are usually divided into episodes and in this perspective you can chop them into equal parts as you see fit.
You can stick to some sort of metric for each such part. Or cram a bunch of events into one pile to get to the right amount. But I don't think such a piece would be complete. It's a draft anyway.
You can start looking for the right size based on your personal capabilities. For example, you can easily write 2500 words in a week and are ready to publish such passages without delays and nerves. Do you have enough ideas to fill that amount of text with meaning?
It is better to write ahead of time to be able to revise what has already been written, then you can be satisfied with 1500 words per chapter. And for some, 5000 words a day is the norm. Just take note that this is done to systematize the writing. To keep yourself organized.