It seems that Jet.com (Ana Amazon-like competitor, I haven't used them yet, so don't know the experience) has a $35 threshold for 2 to 5 day free-shipping.
I've been comparing and buying on either Jet or Amazon recentlly. As a result, I've been buying on Jet more frequently.
Jet has a smaller selection but they usually have a good enough range on the price-value curve that it's not a big problem. Like for like, they are indeed cheaper than Amazon and free 2 day delivery is always a plus. Of course their model is lower prices with a bit more delayed deliveries.
I just ordered a few things from Jet.com and it was split into 3 shipments. A shipment of 1 item came within 2 days. A shipment of 3 items is on its way somewhere (although the tracking number gives no real details). The final shipment of 1 item is still 'processing' 4 business days later. It was supposed to be 2-5 day shipping, but I don't see the third item getting to me by tomorrow. We'll see, I guess.
Also your discount increases the more items you add to the cart, so jet actually encourages you to make one big shopping cart with their system.