Yep - that's common for coinstars. I used to do my grocery shopping at hours when the stores were mostly empty and rarely found anything at all in the coinstar. Then I noticed the better finds occurred when the store employees were too busy to check the coinstars, so I adjusted my shopping hours. I found a few at the local walmart - but then the homeless caught on to the reject tray and now they camp out in front of the machine waiting for someone to use it. When they get silver, they go inside and spend it - which is why I always pay cash at Walmart to get change back. When I hear silver dropping into the reject tray at the grocery stores, I'll stand beside the coinstar looking at the movies for rent in the Redbox or at the Lottery ticket machine, until they finish.
Being retired also helps in that I have more time to stop and buy just a few items - and can check the coinstar when I want. When I worked, I was more likely to buy more items at fewer visits and go to the grocery store only on my way home from work.