My feed consumption doubled with a second feeder - confirming that not all were getting enough time at the 'buffet' in a larger group. I like the 24/7 feed and yes it's much less waste/spilling!
I've got a plastic dog feeder the dogs didn't like (chewed the top off). I used a can to prop the 'door' open - and a piece of siding on top. Works great - only disadvantage I found was only a few would eat at once - when I had 30 in the pen I wasn't sure all were eating enough. Put a second...