I have had very limited experience in the areas mentioned. I am enjoying this thread. That being said, This excerpt explains at least one reason why reboot after format makes sense. I certainly cannot comment on the validity of the statements but offer it up as "grist for the mill".
From an article found on the following website..
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5. Reboot after format (back to Windows 9x)
Although it is possible to enter Windows from this
environment (provided that you installed HIMEM.SYS),
we do not recommend doing so at this point. Remove
the system diskette from the floppy drive and reboot
the system and enter the regular Windows environment.
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If you were preparing the new partition inside a
DOS Box, rather than in real-mode DOS, you could
access the volume and proceed to the next step
(XCOPY /CLONE), but you should still reboot now.
Because after a volume is formatted, it remains
in the so-called
"MS-DOS compatibility mode" where
the disk I/O cache is disabled. Without a reboot
after a format, file access to the volume will be
extremely slow --- the XXCOPY action would take
literally hours rather than minutes without reboot
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Smitee