DrE
You are mixing things up a bit.
1500m is the ICAO minimum for VFR. It is also allowable for VFR if you have an IMCR or IR. Maybe the old UK (not JAA) CPL also because with that you got a honorary IMCR...
If you are lost (let's not use the much longer CAA name for it) every 1 minute in 1500m, you will be lost every 2 mins in 3000m. That's not a whole lot better. Nobody will be flying 1 or 2 minute legs with the stopwatch
"the correct technique to navigate in such conditions is to build up experience in better conditions first, then apply said experience along with further training (such as IMC) to do it safely"
No, we are talking about a plain PPL here. An instrument qualified pilot (IMCR or IR) has far better ways to navigate, and isn't going to be kerb crawling in 1500m or 3000m looking for villages, hedges, roads, lakes...
Building up experience will never let you see what you can't see. Unless you mean building up knowledge of one's local area, which is fair enough (I could fly in 1500m visually around where I live for sure) but is useless relative to PPL privileges which extend a bit further than that!
I wonder how the French (to give one of many cases) handle their PPLs' ability to fly above an overcast layer. Anyone here know the French PPL training syllabus?