Although new data from ShipMatrix shows that fewer deliveries are arriving on time than during the remainder of the year, they have improved over the same time in 2015. Hills is optimistic that retailers' in-store pickup services will also run more smoothly during the busy final stretch before Christmas. During the Black Friday to Cyber Monday period, there were fewer roadblocks when customers placed orders.
Both the major shipping companies and retailers are beefing up their staffing to meet growing demand for online shopping. Online sales are expected to grow 11 percent this holiday, according to Adobe Digital Insights.
Hills noted that as the holidays draw closer, many major retailers push their delivery deadlines later. Sometimes, they'll decide to do so because they're falling short on their sales goals. Other times, they realize they can handle more volume than they'd planned for. They can roll out faster shipping by paying out of pocket for pricier delivery options, or shipping from their stores, Hills said.
The number of packages delivered within five days has improved between 4 and 5 percent every year since 2013, according to StellaService's data. Heading into the holidays, traditional retailers' delivery speeds were just under four days, on average.
"We've definitely seen speeds come down," Hill said.
That's especially important as consumers demand speedier shipments at a breakneck pace. A survey released by Deloitte earlier this season found just 42 percent of shoppers characterize three- to four-day shipping as "fast." That's down 21 points in just one year.
For a list of 28 major retailers' deadlines for standard shipping, see the infographic above. Retailers whose deadlines do not specify a time either did not provide an hourly cutoff, or have not given an explicit deadline. For some companies, StellaService calculated their cutoff dates by using the year-round shipping information.