I think 4 rows of ball bearings is pretty standard.
I guess you dould go down to three for really cheap bearings, but never used many or taken any apart.

But yeah 4 is fine.

The other thing to bear in mind is that you probably do not need to do any of the 'standard' upgrades.

Before changing any original hardware - actually use the machine - fairly extensively - ad see if there are any areas that actually NEED changing.

In my experinece most printers run fine with original parts and the upgardes make little or no difference.

You need to bear in mind that people on facebook groups and youtube - tend to be people who will tinker and change things - regardless of whether they need to or not.