What kind do you have? Mine was an old circular beast, but that was probably 20 years ago!My last place was like that and I wouldn't even leave a crock pot on low without being around it. Surge strip maybe? On mine I can choose the heat setting, so maybe a lower heat even though it's for a longer time? The bigger trays and more open body really helps push the air around too, so things take less time that the smaller circular ones.
One thing I love about drying kale, spinach, and swiss chard is that it dries super fast. A matter of just hours. Shredded zucchini/squash too. The smaller the bits the better. And my tomato purees are usually done in one day. The more sugar something has, added or natural, the longer things take to dry so I did more apple bits or slices at the old place. I could always plump them back up easily to make pie filling whenever I wanted. (if they didn't get eaten first)