Is loading 4 cars on the first day of training common

So on my first day I was given 4 cars to fill and by my boss and the guy training me said that's too much for someone who's new to the job. Halfway through the day the trainer was told to have me do it on my own which I couldn't keep up since I was having trouble with which shelves were on what side. At the end of the day I was told by my boss if I couldn't keep up then they don't need me. They haven't given me another day of work since