I really would not tell a fix number for it. It depends on the type and kind of Graphic information you need to get the job done.
On top of it, there are at least two completely different approaches when it comes to AC Versions: The International version uses the most typical ( almost generic) and the US Version uses it's own.
I find the Int more flexible and complete, and the US compact and a bit "fragile"
In short I would use one PS depending on Scale, Type of Drawing (Discipline: RCP General, Finishes, etc...)
All of this I compress it in something I like to call: Model View Style.
Nando Mogollon
Director @ BuilDigital
nando@buildigital.com.au
Using, Archicad Latest AU and INT. Revit Latest (have to keep comparing notes)
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