94 e500 doors need a little oompf to close

[PutPutPut]

Hi,

All doors on my 1994 e500 need a little more oompf to close than expected. Two things to note, first:
- all my doors appear properly aligned, flush with the body
- they close smoothly when a window or another door is open

Searching suggested to first try closing with opened windows.. and that works. Unfortunately, none of the threads mention how to fix that particular instance, they go on to determine the latch and striker plates were dirty, or full on hinge alignment was necessary, etc. (for example: W124 Door Alignment --- it's a coupe, but parts still seem to apply).

Would losening the striker plate slightly and readjusting be the right way to go? Am I supposed to adjust all four striker plates, or just guess one and have fun? Post #6 in the thread above says that such airtightness is a good thing. Perhaps just leave well enough alone?

Thank you for your time!