Standing Metal seam Detail at change of pitch

I am having a standing seam metal roof installed on my existing home. at one end of the house the roof pitch changes from about 6/12 to about 3/12. The roofing contractor used a continuous sheet, apparently cutting the standing seam and tucking in seam below the cut (the flatter section) into the seam above the cut (the steeper section). Searching the internet I was unable to find any photographs of a roof with the above mentioned detail. I did find a detail that uses two sheets and "Z" flashing. Is the single sheet installation over a change in pitch from steeper above to flatter below an accepted detail. I called my contractor and he said that is how he always does it. I still have some concerns

I have seen people do it that way successfully. However, my recommendation is pitch change (transition) flashing. I would suggest really looking closely at it to see how water will travel and evaluate possible risks.