File system update after DEL?

#1
I'm a little surprised. I delete a file and re-create it and it still has a creation date of months ago.
Code:
v:\> echo %@filedate[iffy.btm,c] & del iffy.btm & echo foo > iffy.btm & echo %@filedate[iffy.btm,c]
2017-06-22
Deleting V:\iffy.btm
     1 file deleted
2017-06-22
 
#3
I'm sure it's very lazy about removing it from the disk, but I'd expect the FS to be updated immediately. It worked better on another file
Code:
v:\> echo %@filedate[f1.txt,c] & del f1.txt & echo foo > f1.txt & echo %@filedate[f1.txt]
2017-09-15
Deleting V:\f1.txt
     1 file deleted                8,192 bytes freed
2017-10-02
(and on a few more).