This is the only correct take.

…except during busy holiday time and in other situations when USPS skips initial scan and the first update after the above can be when the item is in transit and already in another state.

I find “in transit” more useless because they stop updating it randomly and then it just appears at my house. And takes 8 hours for them to update to say it was delivered. Nothing to do with holiday rush since it happens year round.

Used to work CS for a popular shipper in the Southern & Northwest US that also had physical stores. They ONLY shipped USPS. This is 100% correct. People would call with this issue all the time. Package would be packed for a week, call the store and ask "Hey, you forget to ship this order?". The answer was always "Oops, yeah we have it". Thankfully, they've gone under now.

I ship stuff on eBay all the time and I try my best to avoid marking orders “shipped” it can get messy and that’s how you end up with delays. I print labels and ship the same day whenever it’s possible

This is the correct answer. Thank you!