Instant-delivery startups promising to ferry groceries to customers in 15 minutes or less have rushed to expand in major cities like New York and Chicago in the past year. But they’re burning far more cash in the U.S. than in other countries where they operate, causing several of them to test major changes to their business model—including longer delivery windows that could allow the startups to pack in more orders per trip.

One example is Jokr, last valued at $1.2 billion on paper, which told investors in the fall it would experiment with slower delivery times and a subscription service to reduce its heavy losses, according to a person with direct knowledge of the matter. In August, its third month of operation in New York City, the one-year-old startup was losing $159 per order in the U.S., according to internal data sent to investors in the fall that was viewed by The Information.