Have you ever struggled with filament that gets stuck on the spool during a print? Not the kind of issue where the filament is tangled, due to the end crossing below another strand during loading or unloading. But the kind that I saw described by somebody else as "the coil was pulled inward on the spool leading to a ‘wedgie’ " [1].
This week I bought a brand new 1 kg roll of filament, and I was very excited to start printing. The first very small print went well. So I started a larger print, and almost immediately a wedgie happened. I tried a second time, with the same result.
So I unloaded the filament and was holding the spool in my hands contemplating the problem. I was thinking along the lines of building a stand that will be more accessable so I could monitor what is going on more easily. I was rolling the spool over my fingers, contemplating the problem. And then a thought hit me - the problem is that the friction between the spool and the holder is too high!
The first thing I did was sand the little bumps on the inside surfaces of the spool (the parts that make contact with the spool holder). Then I applied a little bit of Q20 oil on those surfaces too, which probably made the biggest difference. Problem… solved! 
[1] https://www.toybuilderlabs.com/blogs/news/13055029-untangling-the-filament-spool
