1/4 pound per day per bird is usually what is stated as "normal". Situations, environments, climate, individuals all can come into play. If the feed consumption was to suddenly double then you might suspect some free-loaders such as rats, wild birds, etc,. Going a little over the 1/4 pound per day # isn't necessarily a bad thing....too far over and it might be.
Free choice feeding is usually best, though it's definitely not a bad idea to monitor how much they're eating.
A recent discussion on an article regarding feeding chickens showed that during the winter that chickens eat more (no big suprise therer) but also pointed out that the percentage of protein can be reduced since the consumption is up....during the summer when they don't eat as much feed to keep their bodies heated then the protein percentage should be higher. Maybe something like 20% in the summertime (more expensive, but they eat less) and 16% in the winter (less expensive, but they eat more)....???
FWIW,
Ed