Not really any changes that I can tell. I order quite a bit of stuff too. It really does depend on where they are stocking the items vs. where you live. Common items are usually at all the warehouses, but less common or items from other vendors that sell through Amazon are a crap shoot. Your best bet is to keep an eye on the expected delivery date when you click on the order button. Another factor is who is shipping it. Usually through Amazons' own trucks is pretty consistent, UPS will be longer, USPS is a total crapshoot.
A couple of weeks ago I ordered some cans of Rustoleum bedliner spray paint to cover a boat trailer I was working on. Sold by one of their vendors. They shipped them USPS. About 6 or 7 days in, I still hadn't gotten the package and the tracking info hadnt been updated in several days. Got online with customer service via chat and they agreed the package was probably lost and issued a refund. Then about a week later, a box shows up in the mail and guess what it is, right after I bought a can locally. Not Amazon's fault.