I made a magsafe mount in black for my Kia and I didn’t like the layer lines on the curved parts, but it gave me the idea to try using wood
I have a 3D Chameleon MMU so I added color changes randomly throughout between two shades of brown. One is wood, one is PLA.
It honestly came out way better than I even expected!
If anyone wants the STL I can provide it!
If the infill is enough to take up the entire purge volume needed to get rid of the previous color, then you are right.
Most of the time there are sections where there is not enough infill to purge what it needs to though
Since it’s not a good idea to extrude filament into open space, it has to build up a structure for that later Purge. That’s why it seems to make a hollow pointless Purge Tower sometimes.
Another factor is the minimum Purge amount. I think that is set in the filament settings. By default it is not zero, meaning it will always create the tower no matter what, though it might be really skinny.
If you add objects that will be created from The Purge material you should see that Purge Tower get smaller when you reslice, or at least less dense