We have gotten quite a few questions recently at the shop (Full Moon Apiary) about using spacers to run 9 frames in a 10-frame box or 7 in an 8-frame box. Here is my point of view.
For a new beekeeper or anyone who needs to have foundation drawn out, it is best to run a full box at least until they draw comb. It can be difficult sometimes just to get them to build on foundation. By reducing the number of frames, you are creating more space and a larger violation of bee space. You will get a lot more bridging between frames and offset comb this way. Once you have comb built you can reduce the frames by one and space them so the bees can fill them. Besides the metal spacers that you attach to the boxes, there are spacing tools that allow you to position the frames. This is generally the way we do it. You can also just eyeball it and do pretty well. At the end of the harvest, we consolidate back to full boxes for storage, and this improves our storage efficiency.
A disadvantage of reducing the number of frames in a box is that bees never seem to build equally so it becomes difficult to move frame locations without jamming comb. I find this most problematic in the brood box where we are constantly equalizing colonies. I do not like to run reduced frames in my brood boxes for this reason.
The advantage of having reduced frames in the honey supers is bees generally draw the fames out deeper so when uncapping you cut less into the comb and have deeper comb for re-use.
When starting with a mix of drawn comb and foundation you can alternate with a frame of foundation between frames of comb. Generally, this does not work well for me as the bees will draw the existing comb out more and make very shallow comb on the foundation. Therefore, I tend to make up full boxes of foundation and let them draw it out before mixing with older comb.
Like everything else beekeeping, we all have preferences for how we do things. If it works for you then that is all that matters.
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