I might start with 2-3 howls, then break out the Sceery Cottontail or Primos Jackrabbit ti finalize the stand.
Normally though, I still use prey-in-distress calls, from October through late March/early April.
December is my toughest time to get coyotes to come to the call. In my areas, Colorado, this seems to be the time of year where coyotes begin to pair up for breeding season, and they seem to have less interest in food.
For 2 years in a row, in December, I was waterfowl hunting the same property, and I noticed coyotes way to the N of me, laying on a snow covered hillside. There were 2 packs of about 5-8 in each pack, and they were maybe 50-100yds apart.
When I looked through the bino's, I could see 2 additional coyotes laying near each pack. Every once in awhile, a coyote from a big pack would get up, walk over and around the 2, then rejoin the larger pack.
This went on all morning, both years, and they would not come to a distress call. The best I got was for a couple of them to stand up and look in my direction when I howled.
I have no way to prove it, but I think the 2 coyotes were females, and the packs were the males. When a male got up, he circled the females, doing a 'sniff' check to see if one was in heat.
Thinking back to my high school years, I would have starved before I gave up an opportunity for sex, lol. Perhaps these males thought the same?