When I did my PPL navs a few years back several of my instructors pointed out some pretty big errors on the Perth VNC (silos on the wrong side of the road and tree farms on the wrong side of the road). I never liked it anyway and always found the combination of WAC, ERC, VNC to be more than sufficient. I carried the VNC in my bag just in case. I suppose that if your entire flight will stay on the VNC (or if you
really need some extra detail) then it may be worth it, otherwise it seems like too much faffing about.
With regards to CPL pre-flight the one hour for planning may seem difficult at first but with practice you'll learn about what is important and what's not. If all else fails use TRACK = HDG (or hazard a guess of 5, 10, 15 degrees of correction) and TAS = GS then revise in the air. Of course, if you finish and you've still got time (or the Testing Officer isn't quite ready) keep working on it semi-discreetly.
Another great time saver (notice that it's not a short-cut): Work out your landing and take off distances at MTOW, 40 deg C, nil wind, a bit of slope (down for ldg up for T/O) and the Declared Density (choose the right season) of the highest aerodrome within reasonable distance. That way you save time having to calculate individually on the day. Be prepared for the Testing Officer to ask you prove it using the charts but this will happen outside of your one hour for planning.
I'd go on but one of the kiddies needs me (and I may be waffling on a bit). See these threads
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Good luck,
FRQ CB