Makes perfect sense and your right finding out which ones go were ? that is a challenge in itself , on plastic models which many use as reference, it seems all most all of them seem to be of the raised variety, however period photos not that we can tell much detail from them seem to show a different story

I do know that the wing skin on the M5 was beefed up and thickened to handle a greater dive speed , a flush rivet on the wing would provide better air o dynamics ? this of course is theory on my part