Should different versions of a patch be threaded to each other?

[Ehsan Mohandesi]

The following discusses the threading of patches.
https://u-boot.readthedocs.io/en/latest/develop/sending_patches.html#sending-updated-patch-versions
I see the following mentioned there.
"Make sure that your mailer adds or keeps correct In-reply-to: and 
References: headers, so threading of messages is working and everybody 
can see that the new message refers to some older posting of the same topic.
Uncommented and un-threaded repostings are extremely annoying and 
time-consuming, as we have to try to remember if anything similar has 
been posted before, look up the old threads, and then manually compare 
if anything has been changed, or what."

Does it mean that when a newer version of a patch is sent, it should 
keep a pointer to the previous version's thread by using the In-reply-to 
field?
I have hardly seen anyone doing this.