In the old days, it was standard to feed at certain times of the day, and only what they would eat in about fifteen minutes. Often part of the ration was dampened, usually with the skim milk from cows. This was fed just before night, so the birds could more readily digest it and have something to tide them over the night.
If you've never tried it, youll find that chickens love a dampened feed mash above all others.
During no-feeding times, wheat middlings and other cracked grains (scratch) was tossed into their litter. This keeps them busy and occupied and allows them, literally, to scratch for their supper.
This 'rationing' of rations was common practice on egg and meat concerns, mind you. They wanted precise control over the bird, it's feeding and to ensure it got the proper amount of feed. Besides, they had little else to do but count chicken feed!
Only after 'factory poultry culture' got going commercially was the idea of constant feeding espoused. Much of what we do as hobbyists is inspired by the very commercial practices we despise. More than you may guess.
24/7 feeding is alright and wont hurt anything, of course. It's okay to do that, especially if your birds cannot range. And it is surely easier on the modern chicken keeper, who surely has other things to do than tend chickens all day. But it isn't the only way.