I was wondering if there's an option in blender like that of UV unfold, to be able to see a "heatmap" for UV distribution like red for stretching and blue for too close UVs. I am quite clear of the workflow in UV editor but this is something I have not come across, I know I can apply the checker, but this is more computer displaying the stretching which I think is a handy tool.
Yes there is an option to display UV distortion. In the UV/Image Editor while in edit mode hit N button to display properties panel and in Display section enable Stretch.
Select Angle to display angular distortion, or Area to display area difference between the UVs and the 3D faces.
In Blender 2.8 the stretch heatmap feature isn't in these properties anymore.
In the UV Editor panel on the top right you'll find a dropdown named "Display". Click on it and go to "Advanced > Stretch" and click the checkbox.
You might want to hit "CTRL+Space" with the mouse hovering on the UV Editor window to go into full screen because this dropdown can be hidden behind another panel depending on your workspace setup, just like it was for me. Happy blending !
Since in latest builds "Display" button is gone to show UV stretch you need to go to sidebar (shortcut key "n") than switch to "View" tab and then under "Display" you have expandable option "Overlays" and under that option you have "Stretching" option which is also expandable and has options to choose between "Angle" and "Area".