Setting Render Time

Deke

I'm doing animation and find it efficient to set a render time with Iray.  I run a test render at full frame and see how long it takes for a satisfactory image to render, then I note the time and use it to set a "maximum time" in seconds. I've noticed on one render that even though I set a max of 120 second, it's still taking 3 minutes per frame to render. Any ideas why Iray would ignore the seconds limit when it worked for a still frame?