What I would like is the ability to turn the rating OFF so I could just practice with it - no pressure!
So a good question might be 'where is a good (free) tactics trainer that isn't rated?' Go do that for a while, then come back here to see if you can up your rating...
My TT rating warbles up and down in 200+ point swings! Down for an hour, up for the next hour... and always I get killed by this problem of getting it right too slowly!
It always shocks me when I get a -5 for an answer I got right. Or when it picks apart something that accomplished checkmate 1 move later. It seems to be focused on bullet chess.