I looked into this a while ago, and concluded that different schools prefer the two different approaches, and there's no absolute right or wrong answer in absolute terms. This doesn't seem to be particularly different for either PPL or CPL.
I think that the right approach is to decide, depending upon the location. For example, flying from two of my regular airfields - Cranfield and White Waltham, the local practices are such that your range of entry and exit routes are fairly limited - so I'll invariably fly to a convenient start point, and take my route planning from there.
On the other hand, if I'm flying from, say, Glenforsa on Mull - where there's no airspace, but there is a risk of nearby low level military traffic, I would most likely climb to a cruising altitude in the overhead, then take my route from there.
It's not hard to look at any airfield, plus your planned routing, and decide which of the two approaches to use. I wouldn't be too prescriptive about it.
G