6m is subject to ionisation that is shaped into something like the surface of the sea - lots of waves. These propagate from the surface and grow to huge sizes by the time they are at upper D and E height. That's why you get different propagation conditions between closely spaced stations. Sometimes, you can actually hear the effect of the waves on the radio as the signals come and go.
I like this very clear description/explanation of 6m propagation. And it describes what I experienced yesterday evening. I had the feeling I was standing near the surf of the sea on the beach watching the waves breaking but just not reaching my feet. No matter what I tried I couldn't get my feet in the water leaving me very frustrated. No it was not a bad dream....it was real :-(
I watched neighbourstation PA0O and several other dutch stations south of me making FT8 QSO's on 6m with PJ4NX, PJ4X (Bonaire) and several stations from USA. However I couldn't see those stations and only did one decode from K2ND (not shure if that was the callsign) at -18dB which is near invisible on FT8. Imagine....
Actually, I just finished assembling the 5 element 6m beam. And it is just a matter of connecting the cables and fit it in the mast. But it was too late yesterday, it already started to get darker and I was too tired from the day of work. Would I have any chance with the beam yesterday evening? I doubt it! Although I don't know how much better a 5 element beam receives? It could be just enough to get my feet wet.....