updating time log with smart values

[Evan Giordanella]

I have automation which adds time to tickets timelog. I want the the log to always reflect business days when possible. However, when the time diff is much smaller than a business day, it logs 0.

I have the following options as part of automation:

{
    "update": {
        "worklog" : [
            {
                 "add": {
                     "timeSpent" : "{{issue.In Progress Start Time.diff(now).businessDays}}d"
                  }
              }
           ]
      }
}

I've tried other options, like logging seconds, minutes, etc but then I lose the sense of business and the time logged is too large. 

Is there a way to have any sort of conditional logic that says if less than 1 business day, to log in seconds/minutes, else log with business days?