Keyboard Shortcut to Cycle through Windows of same Application in Windows 7 [closed]
Scott's answer is the closest one I've found to doing this. To summarize what he said:
Win + n where n is the number position of the application in the TaskBar.Then to cycle through, keep Win down and press n again.
(Updated thanks to @ZYinMD's comments - but also see their 1st comment)
Use AltEsc for fast switching without any GUI pop up
https://support.microsoft.com/en-gb/help/12445/windows-keyboard-shortcuts