I have done it a lot for around a year, but i think than the block list is very limited, because after a will the same "blocked" channels come back again in the list. I have now stopped to use this fake feature. I am sure of it because i regularly block official news or music channels, but they appear again anyway after a wile.
It's the same for the "not interested" feature. I have stop to tell them, when asked, why i am not interested (mainly because i have already see the video). The same already "not interested" videos, already viewed and already liked videos show up again after a wile anyway...