I am not making a salt print today because it is dark and rainy here and my thick/opaque paper negatives require >1hour in full sun or >4 hours toward a bright open North sky. My favorite prints have used a mixture of the two, and there are real differences in contrast, gradation, and maximum dark tones.
They take >14 hours under my single BLB fluorescent bulb, and do not come out as well. I must admit it is tempting to make a good UV printer. I have not used the BLB bulb much after testing it a few times. ( I do use it for some other printing-out processes, but not any more for salt prints. )
On the other hand, there is something satisfying to me about making a print with the sun and not using electricity or modern UV sources. I like judging the quality of the sunlight for printing, checking my print from time to time with the split-back printing frame, and the variation that different days make in the prints. I like deciding when to move the print exposure from North open sky to full sunshine. So I'm conflicted. If I had a good UV printer, I might be making a print right now. But I enjoy the variation and the "natural" aspect of making a print with the sun. I think there is a sentimental aspect to this that probably has nothing to do with the final result, but that's okay too... I will do what I enjoy even if it is not pragmatic or logical!
Alan Greene's book suggests using a developing-out method for making salt prints. He says he prints on cloudy days and that sunny days are for making photographs. Also see the wonderful description of
developed-out printing here. I have never tried this but it seems like a great way to continue forward and be able to make salt prints on cloudy winter days.