A typical week in the office now runs from Tuesday to Thursday, a study of mobile-phone activity suggests.
Analysts Placemake.io and Visitor Insights examined phone data from more than 500 UK high streets from 2019 to 2022.
They found increased activity in many suburban and small towns, which it linked to the trend for working from home.
Seaside towns were significantly busier than before the Covid pandemic.
Mark Allan, chief executive of property firm LandSec, said Tuesday to Thursday was incredibly busy in the City of London, but activity on Mondays was only 50-60% of that level, and Fridays were almost as quiet as weekends.
"We're not going back to how things were pre-Covid," he told the BBC. "We certainly believe there are going to be fewer people in offices for the longer term and we are planning accordingly."
Empty office space
Real estate firm CBRE Investment Management said empty office space in London has more than doubled in the last three years.
The company's head of European research, David Inskip, warned many office districts would struggle if there was nothing but a desk and a computer on offer.
"It has to be a high-quality built environment that draws you in," he explained.
However, while city centres have seen a decline, many towns and suburbs have seen an increase in high street footfall.
PlaceMake.io founder Chlump Chatkupt said: "The places that have thrived have a more-balanced, diverse mix of office, residential and retail.
"Residents are spending more time at home and in their local community, and finding they can do a lot without venturing too far out."
Towns with shops, offices and housing all within walking distance - what planners call a 15-minute city - have done well.