As You can observe last weekend 313 was crowded by whole EU, middle East and North African stations.
Almost whole spectrum filled with weaker or very strong signals over S9.
No idea why people use FT8 instead SSB or CW. Maybe we are too lazy?
Here's new write up by Yoshi-san, JP1LRT. Hope it will help to sort things up.
Otherwise one's neighbour or any other so called "tourist" transmitting opposite sequence will kill all other signals one can copy... Sounds familiar?
Have a good DX coming season