Please define what you mean by "substantial" -- Do you cut your watering down to 1/2 of what you do in the summer during these two months, or less? I'm asking because, on the one hand, Sam Sui (sp?) said to never let Paphs dry out, but on the other hand, according to the charts on slipperorchids.info, I'm led to believe that some Paphs get no water for a month or more -- or very little.
Dot: Normally, November, December and January not only experience severely shortened days here; but, most days are also heavily overcast. There is only a few hours each day of useable light, if that. So, I often skip watering or misting for 2 or 3 days in a row...sometimes more. When I do that, I turn the heater down to 70*F for the daytime high. On winter days that are sunny....or after 2 or 3 (more?), days of no water, I mist the whole greenhouse and water one bench and set the heater to 80*F. There are 6 benches. So, it can take me almost 3 weeks to actually get every bench properly watered once. However, in the summer, I water one bench each day and mist everything else each day. So, in the summer it takes only 6 days to get to everything once, with spot watering for the water hogs to get them through to the regular watering day for their bench. After I water bench #6 in each cycle, I fertilize the whole greenhouse with a low dose foliage fert spray. In the summer, this gets done every 6 days. In the wintere, this gets done every 18 days, or so. Plus, I reduce the dosage by 1/3 for winter feeding, as compared to summer feeding. I also add Epsom salts to the summer feeding schedule and cut it out altogether for the winter. So, from November through January, my plants get less light, less water, less fertilizer and lower temps overall. Sometimes Paphs and Phrags do go completely dry; but I try to avoid that because it causes unnecessary stress which can lead to bacterial rot. It's stress that causes rot, not moisture. Even a dry plant can get rot.
Rick: Yes, this past summer was the first time I spiked my fertilizer solution with Epsom Salts and I did see a remarkable improvement in the colour and growth of most plants. Also, even though I've had this armeniacum for a few years....and it was blooming size when I got it, it's now, (following a summer of extra Epsom Salts), that it's decided to bloom. In fact, I've had a good fall/winter with the Parvi's. I've got more photos to post soon too.