You said you'd like to hear from real hen keepers. Hmmmmm... I'd think that would be most folks here, but after 50 years of doing this, I guess I don't over think this.
I do not provide grit. If all you feed is commercial feed, no grit is needed. Additionally, if your hens have access to sand, pebbles, gravel and grit in the area they are allowed to roam, they get all they need. Chickens have been domesticated for 3000 years and providing oyster shell and purchased grit is a relatively recent concept. Nothing wrong with providing it, if your hens have no access to anything else.
As to providing some scratch grains, it's fine, but at the current pricing, I've about stopped buying it. It's cost is approaching pellet feed, so I see little point. It is often just a few whole or cracked grains and not a balanced feed anyhow. If you want consistent egg production, a quality feed diet is essential.
Chickens absolutely eat more in the winter for warmth calories. I find an average large body hen (5lbs) eats about 6 ounces of pellets (crumbles) per day. Some eat a bit more, some a bit less. Free ranging in a rich environment will reduce feed costs and consumption, but in the northern US, that environment only exists for a few months a year.
I feed them twice a day, if I am able. Once in the early morning and again in the late afternoon. That management seems to work best and produce the best egg results.
When I am gone, I provide free access feeding.
