What are the recommendations as far as how many hives an extractor of a given size will handle? I realize that if one plans to grow you want to buy an extractor which is larger and also that the length of the harvest will vary in different parts of the country, but I am trying to get an idea. For ballpark figures can you say that an extractor of a given size can reasonably handle twice the number of hives as it's number of frames?

2 frame for up to 4 hives.
4 frame for up to 8 hives.
9 frame for up to 18 hives.
20 frame for up to 40 hives.

What as been your experience?

Thank you for any feedback.