Okay, let's say I have a custom module. 

In this custom module I have a pick-list named "Status" with "New", "In-Progress", "Completed" values.

I also have turned ON pick-list history tracking and chose "Time" to track the duration in (instead of "Calendar Days").

Pretty standard stuff, right?

Here's the problem:
A typical KPI is understanding how long a record stays in the "In-Progress" status.

A  Zoho report should be able to average this duration for you.

However, when you are tracking duration in "Time" you are unable to add an aggregate column in your reports that averages the Duration.

You can only average the duration if the tracking duration is set to "Calendar Days".

This limits us from getting an important data point out of our CRM that should be available.