Hello,
No, as I said I used "Last edit" field from Visio fields. I did not use formulas to get the date and time.
So I use this:

When I add a shape to my drawing last edit time, of course, updates. I have no problem with that. My problem is: last edit field also updates when I open the file (even without touching anything, even in read only mode).
And I dont normally use hour, minute and seconds detail. But I added them to show you the problem. Otherwise you would need to wait a day to see last edit field updates when file is opened.
I see that I was not able to be clear what I meant with adding shapes and last edit field updates.
If I create and save a file with only last edit field, last edit field works normal. It does not update just because I opened the file. It only updates If I add or move something.
If I create and save a file with a last edit field plus a shape, last edit field again works normal. It does update when I add the shape of course but It does not update just because I opened the file. It only updates If I add or move something.
So far all behaviours are normal.
However, If I create and save a file with last edit field plus two or more shapes, last edit field updates whenever I open the file too. If you can check, please open the file I uploaded as minimum working example. Open and close the file a few times. You
will see that last edit field is updating with each and every opening date and time. Its not normal.